I've had ths problem with several TV shows too.
I don't know why, but often it helps to open it with a different player.

For some reason, I have two verions of WMP on my PC, so what I used to do, was opening the file with one, turning the audio off, and then opening the same file with the second one, adjusting the sound to the first one.
Seems like a lot of work, but it isn't really.

The TV show I had most problems with were the old McGyver episodes.
Maybe the guy that ripped them did it on purpose to see how inventive McGyver fans were.