<snip>
"lost2ny" <lost2ny@gmail.com> wrote in message
news:1136494334.581750.97800@g44g2000cwa.googlegro ups.com...
>
> I downloaded the program you recommeded and it's telling me some
> interesting things: the missing CPU time is being used by hardware
> interrupts. Since I've never used this program before, I have no basis
> for comparison but that seems rather high. I'm going to run it on an
> identical machine down the hall as soon as it's owner leaves it
> unguarded. That should give me a clue.

Your actions:

help within PE should give you the clue:
"On Windows NT-based systems Process Explorer shows two artificial
processes: Interrupts and DPCs. These processes reflect the amount of time
the system spends servicing hardware interrupts and Deferred Procedure Calls
(DPCs), respectively. High CPU consumption by these activities can indicate
a hardware problem or device driver bug. To see the total number of
interrupts and DPCs executed since the system booted add the Context Switch
column. Another sometimes useful metric is the number of interrupts and DPCs
generated per refresh interval, which you see when you add the CSwitches
Delta column."

From there, you might want to search sysinternals site for more clues.
In google search:
interrupts site:sysinternals.com

-> can be that: http://www.sysinternals.com/Forum/fo...ts.asp?TID=965
from there -> MSKB:
http://support.microsoft.com/default...b;en-us;817472

If not, you can probably see what is responsible by following this:
http://www.sysinternals.com/blog/200...tem-hangs.html