I have the Mk I (with v2.00-beta7 consumer) sitting here on the desk, and it had been playing for a couple of hours or so when it locked up. No audio, no front panel buttons, no remote, nothing happening on the serial port. It was, apparently, completely unresponsive. For some reason (another distraction?), I forgot about it, and just a moment ago, it started playing again. I'd estimate that it sat there, locked up, for about 30-45 minutes (I think). It appears to be operating normally, in all respects that I can discern. Has anybody else had this happen?