A good friend of mine bought a new Sony Vaio with Windows Vista preinstalled.
But there was a problem: every minute or so, the computer would enter sleep mode. So he emailed me to ask if I knew of any issues (of course, I'm the local tech support!) I hunted through bug databases, his event logs and asked the Sony reps here. Nothing. Nada. No issues known.
Of course, Dave is not seeing things, he's not stupid. So he got a replacement laptop, figuring it was a hardware failure. He got it home, same thing! Every now and then it would go to sleep.
As you can imagine he was pretty frustrated at this point, and I'll be honest, I thought he'd hit a nasty Windows Vista bug.
It turns out to be something utterly strange. Here's a snippet from his email to me:
So, I figured out why the laptop keeps trying to go into sleep mode. I have a bracelet with a magnetic clasp. Apparently there’s a small magnet at the top of the screen and a magnetic switch in the heel pad to detect when the screen is being closed. Well, the magnetic switch gets set off by my bracelet!