Apparently, my computer's power supply has gone bad. After having a long conversation with the nice people at tech support, I learned that if I leave my computer on for more than ten minutes at a time, there is a low to medium chance that it will catch on fire.
Since I consider any chance of my computer bursting into flames to be Absolutely Unacceptable, I will be taking a little hiatus from all things computer-related until my new power supply arrives, most likely by Friday.
So, nothing new here until then. Apologies all around.