Mine freezes when playing a playlist for a significant period - eg after around 1 hour, I'll unlock it, and It'll become unresponsive for a few seconds, even though the music continues to play. After more touching of the screen or multiple presses of the Home button, the music stops and I get kicked back to the home screen.
I get the feeling that if I don't mess with it, the music would continue to play...
It's really annoying especially at a party because the playlist has to be started again.
Mine is not jailbroken.
Is there some kind of feedback channel where these types of problems can be reported to Apple?