I have a Roku 3 and my 1080 - 720 problem is slightly different, but I believe it is related. When I power on the TV and go to Settings > Display type, there is no “TV/Monitor” image displayed and no information about the display. At that point, the Roku 3 hangs. After a minute or two it reboots. If I then go to Settings > Display type, there is an “TV/Monitor” image displayed along with the text “Detected: 1080p HDCP 1.4.” If I press the right arrow, a check mark is displayed beside “Auto detect.”
I can then choose either 720p or 1080p, go through the confirmation process, and at the end there will be a check mark beside which ever resolution I have chosen. The selected resolution will remain until the TV is turned off. When the TV is turned on again, Roku will hang when I go to Settings > Display type and eventually reboot.
If I navigate from Home to one of my channels instead of going to Setting > Display type when I turn on the TV, I can highlight that channel. However, pressing OK will not activate the channel and after that none of the keys on the remote has any effect. After a minute or two, the unit will reboot and a check mark will be displayed next to “Auto detect.”
Software version: 8.0.0
Build: 4143
Model: 4200X - Roku 3
Serial Number: 1GS3AK011323
TV: Panasonic Viera Plasma TC-P50ST30
AV Receiver: Yamaha RX-v471