Run a Chkdsk. Start> Run> type: Chkdsk /f/r then hit OK. You will have a message that it can't be run now, would you like to run at boot (Y/N) type: Y then Enter. Restart your computer and let it run.
You can also right click your Local Disk (C:) in My Computer and select properties. Tools tab, Error- Checking > Check Now button. Check the boxes and hit Start.