Thanks for the tips. I've an electrician friend that I could let have
a look inside the power supply itself... it's the original one and I'd
rather keep it than replace it if at all possible. Should I be
concerned about any damage to the motherboard as a result of what the
power supply is doing? Like I said, when it feels like working
properly, the rest of the computer appears to work just fine with all
my games/applications, although I haven't run a RAM diagnostic or
anything like that.
(Until I can get the power supply looked at, I'm thinking I'll just
hook it up to an external switch.)