Do these to clear corruption and repair/replace damaged/missing system files.
Start - type in Search box - COMMAND find at top of list - RIGHT CLICK - RUN AS ADMIN
sfc /scannow
How to analyze the log file entries that the Microsoft Windows Resource Checker (SFC.exe) program
generates in Windows Vista cbs.log http://support.microsoft.com/kb/928228
Then run checkdisk - schedule it to run at next start and then Apply OK your way out then restart.