I made another post about how on this (my second MBA) and on the first one i had, if i left a video or divx to run for 15-20 minutes the fan would go to over 6000 rpm and the picture would stutter. Even youtube videos would begin to stutter. I called the Apple store today (in regent street london) and told them i have to travel to almost 2 hours to get to their store and im pissed that i have already had to go twice and now have to again. I said a 1.6 dual core should not stutter while playing youtube videos for twenty minutes. Her reply was "i am sorry you are having problems, i can assure you if you change it NOW there wont be any problems" i asked what has changed, she replied "the first batch had over heating issues on quiet a few of them but it has been sorted now." Now the MBA slowing down is obviously due to over heating, a problem that i have had with both my MBAs. Before i even got to mention the thing would heat up from playing youtube videos or an episode of Simpsons she sounded like she had her reply ready, as if shed talked it about to numerous others. I will be getting my third (last, if it doesn't work im done) MBA on sat or monday when they get more stock and will let it run playing two films back to back and see if it slows down. It is 1.6 dual core and should be more than capable of running a divx file (not to mention it costs £1200) a file that my brother 3 year old £399 1.0 HP laptop can play just fine.