1. Try to update DivX and XviD decoder, or FFDshow, wich of them you use:
http://forum.bsplayer.org/viewtopic.php?t=3042
and assign the decoders to the specified files (DIvX decoder to DivX movies->uncheck "supporrt for generic MPEG4", and XviD to XviD files->uncheck decode all supported formats.
2. Try to delete the file named BSplayer.your.name.xml in program files\webtech\bsplayer. It contains your personal settings for BSplayer, it will not harm anything else. Then restart the player.