I was playing a simple board game backgammon (no disk IO, no net traffic)
while my hard drive suddenly start to have a flurry of activity like a virus
scanner is running or something.

During this time, the system is sluggish. When I ctrl-alt-del nothing
happens for half a minute and then an error dialog box something about login
ID. The screen stopped refreshing for another few seconds, then I
ctrl-alt-del again and this time got the task manager.

I closed all apps and killed many processes I can see, but still the disk
activity goes on. There are only about 8 process left -- window explorer,
taskmgr.exe, taskeng.exe, rundll32.exe, ...

All processes except idle has 0% cpu time.

I have also turned off auto update, turned off auto virus scanning, etc.
I unplugged network cable, I logged off -- no help.

I logged back on. After a few more minutes the activities stopped.

This is driving me mad. I don't like the hard drive having a lot of activity
when I'm not initiating any disk IO.

Is there a tool that would tell me what process (could be a hidden one) is
generating the disk IO next time it happens?