Hello, I have a Dell XPS420 that's never had problems.. until last night. (We hadn't turned it off.) At 3am, a whine (whirring sound) loud enough to wake my wife was coming from the box, and a yellow light was backlighting the power button. (I believe it's usually blue.) Dell has told me today it could be the (stock) power supply. Anyone ever hear of power supplies failing this way?