It always happens that the original system files in the windows folder can get modified by external softwares .
When these softwares are uninstalled they may get these files corrupted.
When such usual cases happens the user can always restore all the corrupted files from the windows xp cd.
go to start >run>and type sfc /scannow (note that there is a space between the sfc and the /)
A window will pop-up and it will scan for the corrupted files . when an error is found it will ask the user to insert the windows xp cd and then the system takes of the rest , just sit back and watch all your corrupted files being replaced by original windows files.
other options :
sfc /scanonce - scans all protected files only once.
sfc /scanboot - checks protected files every time the system starts.
sfc /revert - returns scan to its default operation.
sfc /cachesize=n - sets the cache size for the windows files in mb.
sfc /purgecache - scans protected files after purging all the windows file protection cache.