I've had bad luck with Toshiba's too. My advice would be to take it back. Now is the best time since everyone is returning stuff. You probably won't even need a receipt. Just get some store credit at Best Buy or Circuit City and you're good to go.
Thanks, y'all. I've wondered whether the unit could be overheating in the entertainment cabinet, since this always seems to happen when the unit's been running an hour or so.