I just picked up Oblivion this week and chugging through it. It was on for about 8 hours today when I started having issues (8 hours of on-time, only 4-5 hours of that actually playing). I saved my game while sneaking through a boat, got spotted, and reloaded the save. The game instantly froze while loading. I turned it off and back on, and now anytime I load a saved game it will freeze while loading. I turned the console off for an hour, turned back on, and it's still freezing. I cleaned off the disc, still freezing. I popped in another game to play for an hour, which played fine. I popped Oblivion back in, freezing.
ARGH!
ARGH!