I am having trouble with my local NBC station in Austin, TX. For the past two weeks sometimes shows pixelate making them unwatchable. Other times it won't happen for a couple of hours. I called Directv customer service and they said the don't see anything wrong on their end. They told me to call back when the pixelating is happening again. The problem with that is that I DVR my shows and watch them later. I rarely watch anything live because I rarely have the time to. I've already tried resetting the box with no luck. And I checked all of my connections and everything is fine. I have the HR21-100 receiver, but I don't know how to check for the signal strength for NBC. Thank you for any help you can give me.