Deferred Process Calls

About 2 days ago I noticed my laptop slowing to a crawl. AFter checking CPU
on task manager I came to the boards and from another related thread
downloaded Process Explorer. Whike there have been occasional brief breaks,
PE tells me that DPC's are taking up about 65-70% of my CPU for hours on end.
I am a pretty good user, but not technical enough to follwo what I read.
Most of what I can find says that something like this is likley a driver
issue. There is nothing in the device manager that shows anything amiss and
I cannot find anything in Process Exploere to help me understand how to find
what the device is that is hogging the resource.

Something in the help files suggested enableing the context swtiches which
runs a continually larger number- in the millions but provides no insight.

How do I find out what is causing this, short of uninstalling and
reinstalling every component on the system?

IBM Tablet X61/ XP SP2 current with updates/ 2 Gig memory/ Core DUO L7500
1.g ghz. Norton 2008 and nothing else funky or odd on the system. Nay help
very much appreciated. I had to close all my other apps just to post this!

Thanks