Start > Run > copy and paste in:
You will need your XP/2000*Grinler disk. If you don't have it and instead only have a recovery CD, there is a work around. View the following link for a tutorial:http://www.updatexp.com/scannow-sfc.html
sfc - system file checker, retrieves the correct version of the file from %Systemroot%\System32\Dllcache or the Windows installation source files, and then replaces the incorrect file.
If you want to see what was replaced, right click My Computer > manage, expand event viewer > system.
It's a safe way of dealing with things like that ;)..let me know if that solves the issue.