voices out of sync

Hi all..

I have a problem with the sound streams (i.e. the two towers).. after a cople of minutes the voices get out of sync with the picture.

Im new with bsplayer and i want to know how to correct this.
at the audio prefs all fields are blank (by default) and i have a couple of options to choose from ( intervideo/cyberlink decoder) and so on.

im using the latest bs player build ( i think) ver 493 jan 2003 and Xvid codec of 30 march 2003

Thanks,

R.