The computer turns on but Windows does not start. The computer does not boot

If after turning on the power computer does not bootThis may be due to several reasons.

■ In the event that the message Invalid system disk appears on the screen at the initial stage of loading. Replace the disk, and then press any key and you cannot do work at home, check to see if a diskette is inserted in the drive of your computer. If a floppy disk is present in the drive, remove it, and then click reset button   on the front panel of the system unit or turn off the computer and turn it on again.

■ The computer may not boot   if the process of loading the operating system stops at any stage, press the Reset button on the front panel of the system unit or turn off the computer and turn it on again, then at the initial stage of the system restart, press the F8 key. A menu will appear on the screen in which you should select the Safe Mode item using the cursor keys in Windows 2000 / XP or by successively pressing the 3 and Enter keys in Windows 98 / Millennium Edition. After graduation win bootdows in crash protection mode check the disks. In Windows 98 / Millennium Edition, for this, select Start\u003e Programs\u003e Accessories\u003e System Tools\u003e Disk Test, and then click the Start button in the window of the disk scan program that opens. In Windows 2000 / XP, open the My Computer window, right-click on the disk icon on which Windows is installed (most often it is C :), select Properties from the menu that opens. By clicking on the top of the window that appears on the screen, go to the Tools tab, click the Run scan button, select the Automatically fix checkboxes system errors   and howling bad sectors, then click on the Start button. Most likely, Windows will prompt you to perform a check at the next system boot, agree to this proposal by clicking on the Yes button. Reboot the computer.

If the computer did not bootthen after loading the operating system in safe mode (to select this mode, press the F8 key at the initial stage of Windows startup) in Windows Millennium Edition / 2000 / XP, you can use the System Restore utility. To do this, select Start\u003e Programs\u003e Accessories\u003e System Tools\u003e System Restore for Windows Millennium Edition / 2000 or Start\u003e All Programs\u003e Accessories\u003e System Tools\u003e System Restore for Windows XP. In the right part of the System Restore window that opens, set the switch to Restore the computer to a state at an earlier point in time (Restore a computer to an earlier state) and click Next. In the left part of the next window you will see a calendar image, in the table of which the dates in which Windows automatically created a “snapshot” of the system are highlighted in bold — it is up to the state for one of these days that you can restore Windows using this program. These “snapshots” are called system restore points. You can switch the months in the calendar by clicking on the buttons with the image of the right and left arrows. After selecting the desired month, click on the date when the recovery point you need was created. In the field to the right, you will see the time of its creation and a short text comment. You can scroll through the list of recovery points by clicking on the buttons with left and right arrows above the description of recovery points. After selecting the desired restore point, click the Next button. System Restore will show you information about the selected restore point. Click the Next button to begin system recovery. Within a few seconds, System Restore calculates everything from the disk necessary informationafter which the computer will restart. After the resuscitation process is complete, Windows will boot as normal with the settings fully restored. System recovery does not mean that after you restart your computer you will lose what you prepared for lately   documents or messages emailhowever, programs installed after the recovery point was created may not start, so you will need to reinstall them again.
  If, when you turn on the computer’s power, sound signals consisting of a series of long or short beeps are heard from the system unit (the image on the monitor screen may disappear), this means a hardware failure has occurred - most likely, computer does not boot because a computer part has failed. Contact a computer repair specialist.

As a service center engineer, I often hear complaints from customers that the computer does not start or does not boot. This describes a variety of problems - from power-on issues to disruptions in loading the operating system. But to be more precise, “does not start” should be understood as it does not turn on, does not initialize or does not work, whereas “does not start” should mean exactly the problems with the system loading.

Let's look at examples of specific symptoms of why the computer does not start.

No response to pressing the power button

Causes

  • There is no voltage in the mains, the power cord is damaged or the power supply is out of order.
  • The power button is damaged.
  • There is no electrical contact in the power connectors.
  • The power management chip is out of order.
  • Damaged internal power supply (on laptops).
  • The chipset is out of order.
  • BIOS is corrupted.

What to do?

  • Make sure that there is voltage in the mains. Check if the power supply is turned on and the cable is securely connected to it. If possible, check the computer with another power supply.
  • To test the button, disconnect the wires from the Power Switch contacts (ON, PWR_ON, PC_ON) on the motherboard and close the contacts with a screwdriver. If the PC turns on normally, the button is to blame.
  • Reset the BIOS by removing the CMOS chip battery and shorting the pins on the socket. Or using the jumper (button) Clear CMOS (other names - CLRTC, CRTC, CL_CMOS, CCMOS).

The computer turns on (fans are running), but there is nothing on the screen

Causes

  • The processor is defective or there is a problem in its power system.
  • The north bridge is out of order.
  • Defective slats, slots or power to the RAM (random access memory).
  • The BIOS flashed.

What to do?

  • Make sure that the processor is not damaged and that its cooling system is connected correctly.
  • Check if an additional four-pin connector is connected near the CPU power regulator.
  • Check the RAM slots in different slots, try replacing them with obviously working ones.
  • Reset BIOS settings.

The computer shuts down or restarts during startup

Causes

  • Overheating of the processor or the main elements of the motherboard.
  • Failure (short circuit) of one of the computer devices.
  • The voltage levels on the motherboard are out of range.
  • BIOS issues.

What to do?

  • Clean the cooling system from contamination. Update the thermal paste layer on the processor.
  • Disconnect all devices optional for starting the computer: peripherals, expansion cards (sound, network, etc.), optical drive, everything that is connected to USB (except the keyboard), RAM (except for one bracket), hard disksexcept system. If the PC starts up, one of the disconnected devices is to blame.
  • Reset BIOS settings.

Operating system loading does not start

Causes

  • System hDD   out of order, improperly connected or not receiving power.
  • Chipset problems (south bridge).
  • BIOS issues.
  • MBR damage or boot files   operating system.

What to do?

  • Ensure that the hard drive is properly connected, operational, and receiving power. Check if it is detected in the BIOS and if it is visible when booting from other media.
  • Reset BIOS settings.

If all else fails, as well as if a power-up problem occurred on the laptop, contact the service.

About operating room issues windows system   XP, let's talk in more detail.

Why may Windows XP start fail?

There are many reasons why Win XP does not load. This is damage or lack of boot files, registry changes, incorrect boot.ini configuration file settings, corruption of MBR (main boot record), and sometimes a combination of these factors. Such problems occur most often due to the following:

  • viral activity, especially associated with blocking MBR and working windows backgroundsas well as due failed attempts   treating such viruses;
  • errors while creating a configuration with loading several operating systems;
  • surface defects hard drive;
  • power outages that can cause damage win Files   in the process of reading and writing.

For a better understanding of the reasons for Win XP boot crashes, we will briefly examine how this process goes.

Windows XP computer boot order

We will not consider the system stages of turning on the PC — receiving the Power Good signal with the motherboard, initializing the devices, and starting the BIOS code, since the problems at this stage are hardware. The start of the Windows startup will be considered the execution of the MBR boot code, to which the BIOS transfers control. So.

  • The MBR finds the active partition in the table and transfers control to the boot code from its first sector (Boot Sector).
  • When executed, the code boot sector   transfers control to the NTLDR file - windows bootloader   XP.
  • NTLDR puts the processor into 32-bit operation mode and checks to see if the sleep mode image (hiberfil.sys file) has been saved on the hard disk. If there is such an image, it downloads it, if not, it reads information from the Boot.INI boot configuration file.
  • If several copies of Win are installed on the computer, a menu is displayed on the screen from which the user can choose which system to load.


  • After selecting the system, the ntdetect.com file is launched, which determines the hardware configuration of the current boot.
  • Next, the ntoskrnl.exe (Windows XP kernel) and Hal.dll (Hardware Abstraction Layer) files, the intermediary between the PC hardware and the Win kernel, are downloaded.
  • The final task of NTLDR is to launch drivers that are marked as bootable in the registry and transfer control to the kernel code. At the same time, the equipment is being initialized, the interrupt controller and the input-output system are turned on.
  • The Windows XP kernel starts the session manager - Smss.exe, which creates the user environment, the graphics subsystem - Win32k.sys, the client-server execution engine Csrss.exe, the logon program Win - Winlogon.exe, the authentication service - Lsass.exe and Services.exe - a service control manager.
  • Next starting up   Welcome screen - LogonUI.exe and user login program in Windows - Userinit.exe.
  • Next, the explorer (Win shell) - Explorer.exe starts, the desktop appears on the screen and the system goes into standby mode for user commands.

How to restore Windows XP boot

Win boot failure can occur at any of these stages. Knowing what follows, it’s easier to understand the reasons that violate the launch of the system.

Master Boot Record Recovery (MBR)

If damaged, the MBR is interrupted at the very beginning, almost immediately after turning on the computer. It appears that a message is displayed on the screen:

  • Missing Operating System - operating system not found;
  • Invalid Partition Table - invalid (defective) partition table;
  • Error Loading Operating System - error loading the operating system.

Or nothing is output.

If the MBR is damaged, both the boot code and the partition table may suffer. To recover the MBR code, you need to start the computer with installation disk   Windows XP and enter the recovery console. For this:

  • place the installation disk in the drive and start the download, when you see the message “The installation program welcomes you”, press the R (restore) key;


  • to work in the console, specify the serial number of Win XP where you want to log in. If you have one system, press 1;
  • enter the administrator password;
  • enter command fixmbr   and press Enter - the boot code will be overwritten;
  • enter the command to exit the console exit.


The partition table cannot be fixed with Win's own resources. For this you have to use third-party programs. One such utility   TestDiskperfectly copes with this task.


Recovery of boot sector and NTLDR bootloader

A damaged boot sector code has the same symptoms as an MBR corruption, and the error messages may be as follows:

  • NTLDR is missing - NTLDR bootloader not found;
  • A disk read error occurred - an error occurred while reading the disk;
  • NTLDR is compressed - the NTLDR bootloader is compressed (not unzipped).

To solve this problem, you will need the recovery console again, where you will need to run the command fixboot.


The same messages can occur if there is no NTLDR bootloader in the root directory of Windows XP. A copy of this file, transferred from another computer under running windows   XP or from the installation disk.

Configure boot configuration (Boot.INI)

If the Boot.INI boot configuration file contains errors, starting Win XP will also be impossible, since NTLDR will not know what to load and with what parameters. The system notifies you of this problem with the following messages:

  • Check boot path and disk hardware - check the disk and the path to the boot partition;
  • Could not read from selected boot disk - could not read data from the selected boot disk;
  • Windows could not start because of a computer disk hardware configuration problem - windows launch   failed due to disk configuration error.

The recovery console will help you out of the situation again. Run the command: bootcfg / rebuild   - it restores the standard boot.INI entries. In the process of her work, everything hard sections   The drive is checked for installed copies of Win. If systems are detected, entries about them are added to the configuration file, and the user can confirm or reject adding the system to the boot list. So it is possible to restore the launch of several copies of Windows.


Registry Recovery

Another reason XP does not load is damage to the registry, especially the System sections, which contain information about starting drivers, and Software, which contains boot control settings.

To “roll back” these two sections to the state at the time of system installation, start the recovery console and run the commands:

rename c: windowssystem32configsystem system.old

rename c: windowssystem32configsoftware software.old

copy c: windowsrepairsystem c: windowssystem32configsystem

copy c: windowsrepairsoftware c: windowssystem32configsoftware

In the same way, you can restore other Win registry keys: Defoult, Security, and Sum.


Recovery boot files

You already know why the files responsible for starting Windows XP lose their functionality. Win in such cases boots almost to the end, but at some point it goes into reboot or ends with BSoD’s. So, error 0xC000021a (fatal system error) indicates the absence or corruption of Winlogon.exe or Csrss.exe. The problems of other files may not be accompanied by messages, but only appear as a black screen during the download process.

If you know which files are missing, you can transfer them from another similar system or from a distribution disk - from the i386 folder. To do this, the computer also boots from the recovery console, where commands for copying and unpacking files from the storage are executed. So team expand d: i386userinit.ex_ c: windowssystem32unpack and copy to folder system32file userinit.exewhere d: is the installation disk.

If it is not known, due to which files, installing the system in recovery mode will help. System files   will be overwritten, and the programs, settings and user data will remain unchanged.

  • Start the computer from the installation disk. When the “Welcome to the program ...” window appears, continue the installation by pressing Enter.


  • In the course of further work, the program will scan the disks and if it detects them copy of windows   XP, will offer to restore. To do this, select it in the list and press "R".


  • After the reboot, there will be several more steps where user participation is required. Including - entering the serial number.


  • At the end of the operation, the files will be overwritten and if the reason why Windows did not boot was in them, the system will restore its work.

Moreover, it’s quite expensive, but without apparent reasons   stopped loading.

It’s good if you can quickly deliver it to the service, but in some situations you have to fix the problem on your own.

Of course, without a detailed diagnosis, it is impossible to find out the true cause, as well as give universal advice, but several of the most common causes can be considered.

What to do if the computer does not boot

First you need to find out at what stage the computer “hangs”, at the stage of self-testing, or when Windows has already started loading.

In the event that the Windows logo appears on the screen, after which the download stops, the problem is guaranteed to be damaged operating system, with the hardware of the computer, most likely everything is in order.

Sometimes it helps to load the last successful configuration. To do this, immediately after turning on the computer and feeding bIOS system   signal of successful completion of self-control (one short), you must start to press the F8 button. In the menu that appears, select "Download the last successful configuration." If after that the system starts up, the problem will be solved.

If the Windows logo does not appear, but the computer passes the test, you can try to boot from external mediafor example, from boot system disk   with windows. If the download went fine, the problem is most likely in the operating system, after reinstalling everything should work fine.

If the computer starts up at the self-test stage, the problem lies in the hardware. You must listen to the signals generated by the BIOS using the "tweeter".

Depending on the signals given, you can try to determine the cause of the failure:

  • One long, three short - a video card malfunction. The first thing you should try to do is to pull out and insert the video card into place, check if additional power cables are connected to it, if any. If this does not help, you will have to contact the service.
  • Three long ones are a memory error. Remove one of the modules and try to start the computer again. Remove both memory modules, if there are two, and try to insert them again in the same slots, or in other free memory slots, if motherboard   Installation in all slots of one type of memory is provided.
  • One long and one short, repeating short, continuous - a malfunction of the motherboard or processor. Have to contact the service.

On a number motherboard   early years of release may help bIOS reset. Find on the board a jumper (jumper), consisting of three pins, under which is written Clear CMOS. Move the jumper installed on it to another position (for example, if it is now installed on the first and second contacts, rearrange on the second and third) for a minute, then return it back. Try to start the system.

Sometimes even a method such as removing the network cable from the power supply helps, wait a minute and reconnect. This is due to the operation of the power supply protection system against voltage surges.