Chkdsk
From HowToGeek
The chkdsk.exe utility included in Windows allows you to check your hard drive for errors as well as fix problems.
Overview
Using the command is simple, just open a command prompt and type in the following command to see the syntax:
chkdsk /?
The most command syntax is the /F flag, which tells chkdsk to fix the errors:
chkdsk /F driveletter:
In Windows Vista, you will need to open an administrator mode command prompt by right-clicking on the Command Prompt item and choosing "Run as Administrator"
Syntax
CHKDSK [volume[[path]filename]]] [/F] [/V] [/R] [/X] [/I] [/C] [/L[:size]] [/B]
volume Specifies the drive letter (followed by a colon),
mount point, or volume name.
filename FAT/FAT32 only: Specifies the files to check for fragmentation.
/F Fixes errors on the disk.
/V On FAT/FAT32: Displays the full path and name of every file
on the disk.
On NTFS: Displays cleanup messages if any.
/R Locates bad sectors and recovers readable information
(implies /F).
/L:size NTFS only: Changes the log file size to the specified number
of kilobytes. If size is not specified, displays current
size.
/X Forces the volume to dismount first if necessary.
All opened handles to the volume would then be invalid
(implies /F).
/I NTFS only: Performs a less vigorous check of index entries.
/C NTFS only: Skips checking of cycles within the folder
structure.
/B NTFS only: Re-evaluates bad clusters on the volume
(implies /R)
The /I or /C switch reduces the amount of time required to run Chkdsk by
skipping certain checks of the volume.
