disk access during boot



Lately when I boot my PC it accesses the hard drive at least 3 min at full blast. During this time it is impossible to do something with the computer except to wait. There is practically no processor activity.

I cleaned my PC of obsolete files, cleaned the registry of obsolete entries, etc..
I used a defragment tool, but all to no avail.

My PC runs XP Professional SP2.
Processor: AMD 1500+ (yes, I know: rather oldà
Memory: 512MB of RAM

My question is: is there a tool with which you can see which proces accesses the hard drive?
.