We have suffered through this problem for the past several months. It happens every time I watch an NFL game on Fox. Audio drops do not happen during game action unless a special graphic is on the screen. It doesn't happen in commercials. Yesterday I was watching the San Francisco local Fox station's after game show and the sound was breaking up so badly that I had to turn it off.
I initially assumed that the problem was originating at the local station level. That, however, did not explain why the national broadcast was dropping the sound during the graphics overlays. And now that I see that Muckrak3r is having the same problem in Texas it appears that it is a Dish Network problem.
The drops were happening on my VIP733 in my home theater. I was remiss in not checking whether the drops were happening on a different receiver -- the VIP633 in my home office. Next time I will do a more thorough investigation.
I have not yet called E* or the local station. I am very interested in seeing how many others are having the same problem and if there is a solution.