Can you try HDMI direct into the TV or component direct into the TV Instead?
I probably don't trust your Yamaha receiver.. It's another story if this still happens if the 722 is connected directly though. I am connected directly into my LG 32LC2DU and I don't seem to see the same problems (oversat).. My TV settings are pretty much default.
My signal strengths are:
110 TP 11 - 54
119 TP 11 - 65
61.5 TP 02 - 48
I have to go back and realign/peak my dish, but I don't have any outages or issues. This is with the 'new signal meter'.. Your 722 should have that as well.
Signal strength shouldn't affect your picture provided you see at least a 40 (maybe even less is stable with the new gauges).
I better be able to trust my Yamaha, it's 2 months old. Actually my Toshiba HD-A20 and ex-cable play beautifully through it. IF Dish doesn't we have a problem.
As far as trying HDMI direct to the TV, maybe this weekend when I can pull the cable and re-hook. That's why I ran component direct. Component for "plain" viewing, HDMI for "Theater".