The reason they don't finish is that they are interrupted when some other process changes the contents of the hard disk in some fashion. This could be almost anything as many programs remain active in the background and update a time stamp once in a while or perform some other type of disk access. Making any change to any file system on the hard disk invalidates all the information defrag collected during its first pass so all it can do is start over at the beginning.

If you stop all processes running on your machine, as outlined above, except for Explorer and Systray, and then start your defrag, it should run to completion without interruption.

Windows defrag will complain if you haven't run ScanDisk for a while. That's why I recommended running ScanDisk first. Perhaps the Norton defrag utility won't check to see that all your file system pointers are valid before it begins. Of course if Norton bypasses that check, you might not want to rely on the Norton defrag utility.

      - Mark