Hi its a long Process
NOTE : Be careful while u r doing these steps
If the file system is damaged, you can use chkdsk /r command to repair the volume. However, if you use the chkdsk /r command, you may lose some data.
You will need the Windows startup disks or the Windows installation disk
To repair the volume, follow these steps:
Start your computer by inserting the Windows startup disks or the Windows installation disk if your computer can start from the CD drive.
When the Welcome to Setup screen appears, press R to select the repair option.
If you have a dual-boot or multiple-boot computer, select the Windows installation that you want to access from the Recovery Console.
Type the administrator password when you are prompted to do this.
Note If no administrator password exists, press ENTER.
At the command prompt, on the drive where Windows is installed, type chkdsk /r, and then press ENTER.
At the command prompt, type exit, and then press ENTER to restart your computer.
After you repair the volume, check your hardware to isolate the cause of the file system damage.
If this procedure does not work, repeat it, but type fixboot instead of chkdsk /r in step 5.
this problem occurs when you try to update drivers in the computer..sometimes windows XP cannot update the driver and that corrupts system.ini file as it has a lot of bad entries..Due to this you will get this error mesage..No its not due to virus.its due to an attempt to change system.ini file
Windows could not start because the following file is missing or corrupt: \WINDOWS\SYSTEM32\CONFIG\SYSTEM
That means the System Registry Hive has become corrupted.
There are two ways to get back up and running. The easy way which doesn't always work, and then there is the hard way.
Easy Way --- Note that this doesn't always work.
When you are booting your system, press the F8 key during the start of the bootup sequence, meaning after it does the Power On Self Test.
Once you press the F8 key, you will be taken to a Menu. Select "Boot Using Last Known Good Configuration".
It will now attempt to load Windows XP using a past set of configuration files.
If that doesn't work, there is the next step....the hard way.
Hard Way
Boot your system with the Windows XP Install CD, let the system boot into the Setup. Once in the Setup, choose to run the Recovery Console.
You will now be presented with a screen similar to good old DOS.
First, we will recover the System Hive.
Now, type in the following commands with pressing Enter after each line.
md tmp
copy C:\windows\system32\config\system C:\windows\tmp\system.bak
delete C:\windows\system32\config\system
copy C:\windows\repair\system C:\windows\system32\config\system
Be very careful when you are typing in these commands, one wrong move, and you have, broken Windows XP.
Also, change the C in the commands to whatever your Windows XP drive letter is.
Attempt to boot the system, if it doesn't boot, get back into the Recovery Console and do the following commands.
md tmp
copy C:\windows\system32\config\software C:\windows\tmp\software.bak
delete C:\windows\system32\config\software
copy C:\windows\repair\software C:\windows\system32\config\software