Out of nowhere the processor utilization caused by DPCs on my box jumped from a few percent to 40%-50%, turning my PC into a very attractive boat anchor. The question was, why? What was causing this to happen? I never found an answer, and as mysteriously as the problem arrived it vanished.

While I was wrestling with the problem y'all suggested all sorts of potential causes, including faulty hardware (couldn't find anything and I hadn't changed anything), a misbehaving driver (why would one suddenly start causing problems and then stop?) and bad ju-ju. The last may be the best explanation of all.

I had several culprits of my own in mind, the most compelling being 's automatic update service, but the problem vanished before I could find any solid proof.

Reader Gary Lavery recently wrote to tell me about a similar mysterious problem where something was chewing up cycles on his PC, but unlike my DPC problem, Gary seems to have identified his gremlin.

Gary says that periodically his machine (a Inspiron e9400 laptop with XP Pro and 2 GB RAM) would freeze and the disk light would go on solid for 30 to 60 seconds.