[Thinkpad] OK, not a Thinkpad issue, but bear with me... Any ideas?

[RWM (Out of the Office)]

After a scheduled boot time defrag, my primary Compaq desktop has 
developed a repeated black screen (could be blue; too quick to see or 
read) reboot after performing an apparently successful "scheduled disk 
check" from the partial Win2k splash screen.

It POSTS OK, boots through BIOS OK, boots through the black and white 
zipper OK, boots through the Win2K splash screen with blue progress bar, 
then proceeds to the repeated "disk check has been scheduled" phase, 
completes this successfully, then crashes.

I have tried booting to "last known good configuration" and safe mode, 
same outcomes.

Any ideas on this?  I have the Win2K CD, so can try a recovery, if 
that's likely to be useful.

Yes, I have Ghost backups, but of course now have no client on which to 
recover them. 

- RWM, from a Thinkpad...