Vista 64 bit occasionally freezes-my last Vista problem to be resolved!

My Windows 64 bit Ultimate Vista partially freezes temporarily. The HD light comes on and
is steady. It always releases and while its not a show stopper, it is a pain. Whatever I
am working on at the moment freezes but I can still do other things outside of the window
I'm working on. The Event Log does not record an event when this occurs. This may be a
problem unique to the 64 bit version as I know someone with the 32 bit that is not having
this problem. A search of Microsoft finds only freeze issues related to installation.
Anyone figure this out? I know I'm not the only one with the problem.