Profess to be no expert, but here goes. I'm running XP, Nortons 2002. Had similar problem and did all the above. I got to 80% before defrag quit. I then did another run at defrag, then another before Nortons accepted 100% completed. Initially I ran Nortons, but then tried XP to defrag. Windows advised all was now well, however Norton's disagreed. Got me tossed but all is well now - for the time being!