Bob, I'm afraid I spoke too soon.
The crashing problem is back. It crashes 100% of the time if the server is in, or changes to, the HTPC-Video zone. All other zones are fine.
It did work successfully yesterday in that zone, I checked, and nothing has changed since yesterday, so I have no explanation. Nonetheless, the issue is definitely not resolved.
Interestingly, the crash (as I said before) only occurs if "app follows server zone changes" is on. If I turn that off, there's no crashing. If it's off, I can even use the little control in JRemote to change to the HTPC-Video zone and it does not crash.
If "server follows app zone changes" is on, all works well with no crashing.
If both settings are off, also all is well with no crashing.
So the issue is only with "app follows server zone changes" and only with that one zone.