The DTV tech finally made it yesterday (4 hours late) and ended up having to switch dishes and that solved the problem. Turns out, I had an old HD dish. He switch couplers and the receivers and the b-band converters and none of it worked. The new dish did the trick. They must hate that 771 error because it seems like every person's solution is different.
FYI - the channels all came in fine on my HR20 but not my HR21. I fugured it was the receiver but I was wrong.