divx and xvid files lack sound in bsplayer

I have a problem with audio in divx and xvid files when i play them with Bsplayer or Media player: there is no sound at all. What makes it weird, is that sounds work fine with Divx player. Mpegs work with all of the players. What could cause this kind of behavior?

I have xvid 1.0.1 and divx 3.11 Alpha, 4.12 and 5.11 versions installed. Divx Player's version is 2.5.3 and I have the most recent version of BSPlayer. My display adapter is radeon 9700 with the latest Catalyst installed.

Thanks in advance