Why not try System File Check SFC /scannow to repair O/S first ? http://pcsupport.about.com/od/toolsofthetrade/ht/sfc-scannow.htm

Then if this does not work do a “Repair” install…which is not the same as formatting HDD with clean install of Windows. http://www.michaelstevenstech.com/XPrepairinstall.htm

Either way…let me know how it goes…