Well just recently my MacBook (bought 2/17/2007) started shutting down by itself. Seems to happen after long use (3hrs) and when it starts to get hot. Also noticed screen doin a "fizzle" when using a thumb drive. no idea. Anyway went to Apple and dropped it off. They said they will run some stress tests on it and get back to me. I know there are a few things out there about this but wondering if any of you have experienced this recently or at all? No warranty either. sux. So if it is a logic board issue not sure... or if its a heat sink issue? Not sure what that entails to get it repaired. I was not expecting them to take the MacBook right then and there so i was sorta concerned as it has everything but... want to get it figured out.