I run avg as well but they miss a lot of trojans and worms and trend-micro is good at that.
This info is not only good for your troubleshooting now but you want to run an online scan once every week or 2. At some point in the future i can almost guarantee you that trendmicro will find what avg wont!
Course it depends on how much you use the net and where you go. There are safe places and there are not so safe places, something to do with w...z is a good one, lol.
But you can even pick bad stuff up in good places too.
the power supply doesnt ring a bell, might be a cheapie, did it come with the case or the whole system?
You might want to check out your power supply. You need a multimeter, digital or analog, they are real cheap. You can get a good tutorial for power supplies at techrepublic.com. Its a great professional place, you do have to sign up but they never email you, ever, so its worth it just to get the tutorial for power supplies.
Its there last time i looked, a few weeks ago.
Good advice + great people = tek-tips