Guys, I'm haveing a problem with my wife's PC that I can't figure out. It seems recently it shuts down at random times as though to "stand by" mode. The power light just blinks on and off. Problem is nothing but unplugging the damned thing and replugging back in gets it to restart. I'm thinking mabey an overheat issue?

The system is not a performance rig by any means, just something for the wife to web surf. It's got XP home. Never had any probs in the past until a couple of days ago. Any ideas?