And we’re back!
It was the power supply all along! According to the power supply calculator, I should have at least a 400W power supply — more like 450W. My 300W power supply was severely under-powered for my system.
I went with an Antec SmartPower 2.0 SP500 500W power supply. It’s actually very nice. It’s quiet as a mouse (the fan only runs when necessary), saves power, and has a very nice modular cable system that supports standard IDE drives, SATA drives, PCI-Express cards, as well as a PCI-E graphic card connector (for future upgrades, perhaps).
While I was at it, I vacumed my system. All that dust in there can’t be good.