have you tried the system restore if not try it
if it doesn't help try following:
open the comand prompt as an administrator and type:
if that doesn't help than try this:
In an elevated command prompt, try;
chkdsk C: /f
Where C: is the drive you wish to check.
You'll get an error message about the drive being i use, go ahead and schedule for next reboot and reboot your system.