Well, if I am reading right, Sean is having the same type of issue where DVI isn't working with 780 or 1080. If this is the case, then perhaps it isn't the receiver. I have three receivers in the house, so I am going to pull one off of an SD set and try it.
The receiver I am using on my HDTV did come with a bad OTA tuner, so we took the one out of one of my other receivers till a new tuner arrives.