I have similar problems with TV shows as well, I have come to think that the networks have added some sort of security into them, so you can watch them on your computer but if you try to make a copy of them you get this audio glitch...
It may be because the series isn't released onto dvd until a fair bit later after the original airing and they are trying to stop illegal copyright...
I have seen alot of people with the same issues at the afterdawn site...
Just a theory as to why this happens so much...
Cheers
