I had my old H20-600 swapped out yesterday for a h21-100, he also swapped the lnb on the dish.. Everything works fine, except when using the previous channel button. When you press the previous button about half the time you get a "searching for Satellite" message.. change the channel up or down and then back or press previous channel again and then again and it works fine.. I called the tech and he said he had never heard of a unit doing this.. ever happen to anybody else..