Depends how determined you are to get it working, I guess. Since you watched it for 5 hours, I'm guessing your fairly determined.
Linked from the Mesich page were some advisories, (MS KB's) re defrag problems. Included was advice to turn all other programs off, eg AV, Antispyware, anything that auto updates, elsewhere a suggestion to clean boot the computer, elsewhere the advice that sometimes this behaviour can be caused by a virus or other malware. You can browse those pages, so I won't bother linking, especially since I'm none too sure, myself.
One thing that might be worth a look: in msconfig (Start>run>msconfig) in the startup section, how many applications are set to start with windows?
Have you tried a scan disk, including "fix any errors found"? Hope you haven't, yet, because it sounds like a real good place to go next.
Are there any tasks in taskmanager that might be trying to run at the same time?