Very weird issue with my proc (x2-4200+)

[avi85]

I have an x2-4200+ and ever since I installed vista I have had this wierd problem, where out of nowhere (it can happen 5 minutes after I boot up or not even happen 6 hours after I boot up) my computer will become extremely sluggish and when I go into task manager one core is maxed out yet under the processes tab, "System Idle Process" is in the 90's and no process shows itself as using 50% or even close.
I did a virus scan with a trial version of Microsoft Live OneCare and it didn't find anything.
When I reboot the problem is gone till the next time it randomly starts...
What should I do??? I'm going crazy!!!!

Screenies:
Processes
Performance

 

[avi85]

Bump.

 

[manowar821]

Indexing serivce...? I could have sworn that Explorer.exe would be showing the 50% usage, though.

 

[avi85]

Originally posted by: manowar821
Indexing serivce...? I could have sworn that Explorer.exe would be showing the 50% usage, though.

How can I tell if it's the indexing service?

 

[manowar821]

I'm not sure how to TELL if it's the indexing service, I just always turn it off, I don't like having CPU time being taken up for no (IMO) reason.