This is admittedly a very infrequent bug, but it was a real PITA, so I am reporting it here anyway..
I had JRemote running as top level application on my iPad, when the battery ran low and IOS displayed its modal dialog warning me to plug in the charger. At this point MC totally froze up and stopped playing music and responding to user commands on the IR remote. And since MC was in DisplayView I could not return MC to normal view and so I could not regain control of the regular Windows user interface on the PC, (so I could not manually terminate MC). Therefore the only solution was a hard reset on the HTPC, and that caused the HDMI audio feed to the Receiver to get banjaxed (presumably the hard reset sent a trashed HDMI handshake to the Receiver). So finally I had to do an orderly shut down and restart of the AVR, the HTPC, and the iPad (including the JRemote application), before I could restore everything back to normal !!