OK - I've tried everything that has been suggested:
- I unchecked all resolutions on the HR44-200 except for 1080p
- The "native" setting was already off, as was the audio pass-through to the TV
- The HDMI control setting on the HR44-200 was already off
- I left the HR44-200 on at all times
None of these fixed my problem. I am persuaded to purchase another AV receiver to see if it has the same problem, and if it doesn't, then I'm going to sell the Yamaha AV receiver. I don't understand why it doesn't have a problem switching between the Blu-Ray player and the Roku streaming media player, but freaks out when switching from either of those to the HD DVR and TV. I'm quite disappointed, as Yamaha has been a good brand for me in the past.