http://www.microsoft.com/technet/treeview/default.asp?url=/technet/prodtechnol/winxppro/proddocs/chkdsk.aspChecking a locked drive at restart
If you want chkdsk to correct disk errors, you cannot have open files on the drive. If files are open, the following error message appears:
Chkdsk cannot run because the volume is in use by another process. Would you like to schedule this volume to be checked the next time the system restarts? (Y/N)
If you choose to check the drive the next time you restart the computer, chkdsk checks the drive and corrects errors automatically when you restart the computer. If the drive partition is a boot partition, chkdsk automatically restarts the computer after it checks the drive