One of my 40GB AppleTVs started behaving erratically. I am fairly certain it has something to do with getting too hot. If it has been unplugged for a while it will work normally, as expected. But after it has been on for maybe an hour or so I start getting strange artifacts in the video (looks like tearing, or little glitches in the menus and such), and soon after it will lock up. A restart won't help - only unplugging it for a couple of hours to cool off. It gets very warm (hot?) to the touch - but this is difficult to quantify. To preempt some questions: it has never been opened or modified or hacked. It is sitting on an exposed shelf (not in a cabinet) and it is not on top of or near any other devices. I have also tried it in two different rooms on two different TVs. So my first thought might me a fan of some sort not functioning, but does it even have a fan? Anyone have any thoughts on what it might be?