[afremont]

Update, just before reaching the four hour point, it suddenly stopped playback and went back to the main screen. The myth backend messages indicate that the Pi asked to close the stream. This message appeared at the end of dmesg output on the Pi:
[14220.056732] vchiq: 0: ignoring ERROR from callback to service d00c

I don't know what that means exactly, but it appears to have caused OE to stop playback. Everything looked fine until that point. Still almost 4 hours of good playback is something that I haven't seen in a long time. I'm really beginning to think that adjust refresh rate being disabled has something to do with the problems I experience. I'm going to disable refresh rate change, turn on debugging and reboot. Then I will start a live TV playback and stop it when/if problems occur. I will then post the entire log thru pastebinit.

EDIT: As for the 1080i thing, it appears that OE wants to drive that display in that mode all the time for some reason, not just after starting playback. Adjust refresh rate doesn't seem to be the cause of that. I enabled debug logging, turned of adjust refresh rate and rebooted. I'm experiencing audio stutters right off the bat but so far the video looks like it should.