I didn't see any mention but if he did, maybe it was only between the PC and AVR. I would go direct from the PC to the TV and see if it works.
I would also disconnect power from the TV- if the AVR can have issues, a TV can, too.
HDMI- hate it. Seriously hate it. Even from the structural design of the plug, it's a bad idea. Wide, thin and short with high probability that it will be pulled downward or upward- what's the worst that could happen? Even worse is when it's pulled from the side.