Windows Vista Or Seven System File Check

(sfc /scannow)

Go To Start Search Box And Type CMD  
Right Click CMD.exe and Click Run As Administrator  
In the box that opens type  SFC /SCANNOW (note the gap before/)
Then click ENTER   
If errors are found restart your computer and do the scan again.  
Run it up to three times.
If errors are still showing you might need to use System Restore to
Restore to a time before the errors started