PCB, It's probably not a virus, more likely an electrical problem, especially if the house wiring is questionable and you have an old surge protector. In our last house we had electrical problems that killed a tv, 2 dvd players and a vcr inside of two weeks. It turned out to be a neutral ground fault (Neutral and ground were reversed on the circuit). I repaired the fault, and in addition to that I put everything on a UPS to use it as a line conditioner (it essentially assures you are getting clean power into the system, it acts as an expensive filter in a way, but a $70 UPS is a lot cheaper than a new comp)