I am sure that you don't use XviD decoder in this case. You use FFdshow. So, try to uninstall ffdshow and after that to reinstall Xvid and DivX codecs. All should work ok. If you like verry much FFdshow, then try to update it. MAybe it is an old version you use.
See links from here:
http://forum.bsplayer.org/viewtopic.php?t=3042