You could also perform the ScanDisk in DOS mode.
Click START
Click SHUT DOWN
Click RESTART IN MS DOS MODE
Click OK
After the computer Restarts in MS Dos mode you'll see this prompt:
C:\Windows>
Type in scandisk and press [ENTER]
If you click OK to the SURFACE SCAN then a THOROUGH SCAN will be preformed.
After scan is performed, ReStart your computer in Windows mode.