Broken hardware
Last year, I had the dubious pleasure of losing five hard drives. Three I owned, two others I used. I thought I had used up my quota of broken drives for a while. Last weekend, my PC hung completely on shutdown, which is not unheard of. When I rebooted, Windows failed to boot because of a broken system registry. After digging around a bit, I realized that the drive was failing - fast. Managed to grab some kind of an image of the remaining file system, though. Eventually even the S.M.A.R.T. status of the drive went to critical, but boy was it late!
Last year, I suspected that one failure was heat-related, so I considered upgrading my PC enclosure. Never got around to it, but now I bought a new one when I grabbed a new 200 GB hard drive for a system drive. Turns out the 200 GB ones have the best price per GB these days.
I installed the new hard drive, partitioned it, installed XP, recovered some data. I even went on to install some critical software (read: Battlefield Vietnam), before I decided to play it safe. That is, I went on to swap enclosures before I had spent hours installing all the stuff I need and want. Good thing I did it, because now the bloody thing won't power up. Even worse, it won't even give me an ATX activity light.
I hope I just have a dud power supply, but with my luck, I have blown the motherboard as well. Stay tuned for more sad details as they unravel.
PS. I got the Antec Sonata.