CheckDisk is a powerful freeware tool for searching and repairing disk errors.

It is quite similar to the ScanDisk tool or chkdsk.exe, supplied with the Windows operating systems. You can select either standard or full tests. The full test additionally performs a sector check.

CheckDisk is capable of finding bad sectors on your disk and marking them as such. The program works both with hard drives (including SCSI and RAID) and removable media - it works on CDs too.