NEVER use codec packs.
On the other hand, videolan works on a different way than bsplayer and the other directshow-based players.
uninstall the whole codec pack. then install the following:
Mandatory:
ffdshow
DivX 3.11 alpha (for DivX audio)
OggDS
SubtitDS
Matroska splitter
with the above, you can play almost everything. my default decoder is always ffdshow, it gives a very good quality (better than the official decoders, IMHO). Anyway, you can also install:
XviD decoder and DivX 5.11, with no probs at all. but NEVER use codecpacks.