1. Seems that you use FFDshow to decode video. But probably your version is outdated. Please update it or install DivX and XviD codecs.
http://forum.bsplayer.org/viewtopic.php?t=3042
2. If you use Norton Antivirus please put BSPlayer into it's exclusion list.
http://forum.bsplayer.org/viewtopic.php?t=5351&start=0