I had the same problem (pixelation/audio dropout) with my last HR20-700. I thought it was my old 3 lnb dish, so when d* came out and replaced it free with the slimline, I thought that would clear it up. NOT. So I had the tech come out again and he said it was the receiver and had d* ship me a new one free ($20 is free?). Anywho, I got the new receiver about a week ago, hooked it up and everything was looking good, until today. Same exact problem. Here's the kicker, it only happens on input 1, input 2 is fine.
If anyone can help me out with this it would be greatly appreciated.