I'm having problems with MKV's pausing themselves for up to 30 seconds then resuming after the screen goes grey for a few frames. This tends to happen a minimum of 2 times during playback, usually more. I've tried turning on hardware acceleration, tried the skip loop thing, the threads to 4. Nothing helps. Since, on the whole, macbook airs are the same setup across the board, has anyone else had this problem? Know how to sort it? It's beyond frustrating. I don't want to have to convert them all the time in handbrake to mp4 either.