I'm having much the same problem here - mine locks up mainly when switching playlists,but doesn't seem to have any consistency when it decides to lock up ?? - also having trouble with uploads / syncing seem to have a high lockup / failure rate here , I get a "good" connection perhaps 1 in every 4 attempts ?? I''ve tried serial and usb - upgraded from beta5c to 6a will see how this goes - any ideas anyone ??