Place the Win XP CD in the CD drive.
When Autoplay starts just click the X and close it.
Click Start button, select Run and type in "sfc /scannow" without the quotes
and the system should scan for missing/corrupt MS OS files and replace them
with the originals found on the disk.
NOTES -
The Windows File Protection is constantly checking whether important files
are missing or overwritten and restores them if so. Sometimes it can happen
that a file is corrupted anyway, but then one can use the util SFC.EXE with
the /SCANNOW option to do a full scan of the critical files and restore
those, which has become corrupted:
SFC /SCANNOW
Note this operation cannot complete without the install CD. Therefore it is
important to insert the install CD before launching the above command. If
the install path have changed since the original install, then you have to
change the source path so SFC can find the install files.
Note sometimes the WinXP Home will ask for the WinXP Pro CD, but this is not
problem as long the above condition have been met. Though it might require
that one press Retry several times before the System File Checking begins.
Note to see all options for the System File Checker:
SFC /?
If you need to change the install path
You can change where XP/NT expects to find the XP/NT CD, to do this edit the
registry.
[HKEY_LOCAL_MACHINE \SOFTWARE \Microsoft \Windows NT \CurrentVersion]
Sourcepath=D:\I386
[HKEY_LOCAL_MACHINE \SOFTWARE \Microsoft \Windows\CurrentVersion \Setup]
Sourcepath=D:\
http://support.microsoft.com/default.aspx?scid=kb;en-us;310747
Description of Windows XP and Windows Server 2003 System File Checker
(Sfc.exe)
Note you can save the registry key first by:
On the File menu, click Export.
In the File name box, type SaveKey, and then click Save.
Or create a system restore point prior to editing.
Note: If the registry key is not there, you can simply create one by going
edit > new.
http://support.microsoft.com/default.aspx?scid=kb;EN-US;322756
HOW TO: Back Up, Edit, and Restore the Registry in Windows XP
Disclaimer: Modifying the registry can cause serious problems that may
require you to reinstall your operating system. Use the information provided
at your own risk.
