What codec/filter does BPlayer now use when playing those files?
(rightclick > Options > Filters > Advanced).
To play Div3 you may install the free DivX 3.11 alpha
or (re)install XviD and let it decode DivX content
or use ffdshow instead. All can easily be found on the internet.
If the sound doesn't play it could be that it is AC3-sound. Did you install AC3 filter?
(As mentioned in my Help2Help-post the information that video files are avi-movies is not very informative.)