Problem with Windows ME Scan Disk

The problem is with Scan Disk, :Due to improper shut down: Now whenever I boot or reboot, the system automatically goes in Scan Disk, which is fine, except it never totally completes the scan,
the system will scan, stop the scan, then restart the scan, at times it will continue but never complete the scan, and ofcourse this problem restricts my system from Defragging. !Help!
Thank you
Roy