Windows could not start because the following file is missing or corrupt: \WINDOWS\SYSTEM32\CONFIG\SYSTEM

Last week, my friend's computer has a problem with windows. Every time he turned on the computer, the following error appeared:

Windows XP could not start because the following file is missing or corrupt:\WINDOWS\SYSTEM32\CONFIG\SYSTEM

The Internet advises to run chkdsk command from the Recovery Console. The problem is my friend doesn't have the administrator password, because it is an office desktop PC. The only choice for him is to wait for several days until the computer is fixed?

It is too early to draw the conclusion. What we can do now is to find a CD of WinPE and then follow the following instructions [1]:

If chkdsk does not solve the problem, then the System file should be restored from backups. There are two places to look for the backups, one is the System Restore folder and the other is \Windows\Repair folder.

Go to "C:\System Volume Information", locate and navigate to the folder whose name begins with _restore.

This folder contains many subfolders which have names of the form RPxxx, where xxx is a number indicating the restore point. Locate an RPxxx folder which has the highest number as its suffix (highest xxx) using the command dir command. Then navigate into that folder. Now, there will be a folder named snapshot. Navigate to this folder.

There should be a file named _REGISTRY_MACHINE_SYSTEM, copy this file to the \Windows\System32\Config folder with the name System. To solve the problem completely, MS suggests to replace all 5 files (hives) rather than just the system file, ie system, software, sam, security and default. Then reboot the system. This method works only when the System Restore feature of Windows XP is enabled.

While installing Windows, the setup backs up the System registry hive in Repair folder. If the System Restore feature is turned off, then this backup can be used to restore the System hive. First, navigate to folder \Windows\Repair and then copy the System file to its original location and reboot the system.

The disadvantage of this method is that, since the backup is created during the installation of Windows, by restoring this backup all the system configuration and driver installations made after it will be lost.

How to find a bootable CD

1. Ultimate Boot CD http://ubcd4win.com/index.htm
2. BartPE http://www.nu2.nu/pebuilder/
3. Download Windows Automated Installation Kit (AIK) and create the CD yourself.
   

[1] http://swatrant.blogspot.com/2005/11/windows-could-not-start-because_17.html, modified according to the comment.