to explain myself.
first I'm just trying to help :: thanks for being so kind
neodivx is a soft to encode film in divx format ( whatever codec you use ) but it's really good with xvid!!
secondly: neodivx ( that's the soft name ) use a modified version of xvid to encode with it. I encode with it and I had to install a "normal" version of xvid to play my films because I would have no sound.
it might not be the same problem but what I said wasn't that dumm!! :(
PS: try neodivx.org it might interest you.