Its happened several times to me now, where I'm using my 11" Macbook Air, doing simple stuff like email, when suddenly the display on the Macbook Air and my external monitor suddenly turn white. The Macbook Air apparently is still alive, sort of. I could hear a time machine backup continue running to an external drive. I let the machine sit there thinking that maybe it would come back. The normally very cool Macbook Air got pretty warm. I powered off and back on and it did the Apple sound at startup, but got stuck again on a white screen. I unplugged my external drive and monitor and tried a few minutes later and it came up fine. Is it possible that the GPU overheated even though I wasn't even using it? Is it some strange problem with the GPU driver or Macbook Air hardware? Could it be something strange about having an external display connected? Anyone else experience this?