I've been getting this almost once a day while in the car. It never seems to happen on AC power. The interface just locks up but it keeps on a'playin. Happened again today. Then another weird one... it locked up, and i hit the top button to see if it would power down, but instead it paused. I hit it again to see if it would unpause, and the counter indicated it was playing, but no sound was coming out. It would skip to the next track, and you could hear a blip of the song, then it would go silent again, though the counter was still going. I pulled it out and pushed the player back in to reboot, and all was well. b11 on a Mk2 by the way