Easy way to fix corrupted system files in Windows is to run a System File Checker tool. SFC checks all the Windows system files against their digital signatures and restores any it finds corrupted or invalid. You may have to insert your Windows XP CD on the CD-drive or point another installation source if the local on-disc cache (%systemroot%\sytem32\dllcache) has become corrupted or unstable.
Command line for the sfc is:
After the scan the system must be rebooted.