STOP doing that! A crash during defragmenting is much like me pulling the rug out from under you. YOU may be hurt. My analogy is that you are placing the machines data at SEVERE RISK!

In short, there were issues with older OS's like 95, 98 and ME and Norton's defragmenter that were never resolved. I would just uninstall that program and use the supplied defragmenter.

Another issue is that some machines are aging and small hard disk errors which windows will not handle with any grace will cause this problem.

Do yourself a favor and try the supplied tools in SAFE MODE after you have assured yourself that you can lose all your data on the hard disk.

Bob