What model DirecTV receiver is this on?
One of the things I've noticed that I find very interesting are on my recorded shows and also live shows that if you rewind back to the audio dropout point it is very often gone, not always but alot.
Currently there is still a problem like this with the HR24-500. This is a software problem that will be resolved with the next update coming out "soon".
Those that are always at the same place, are from the SAT feed, but any that don't repeat, have to do with the receiver & software.