Because VLC uses it's own set of codecs, BSPlayer uses what you have installed. Conclusion - there is something wrong with your codecs. Maybe you have too many of them, so they interfere with each other. Maybe you haven't installed ones needed for playback of those movies. Maybe you have broken codecs.
If you provide more information, then someone might be able to help you.
Get GSpot beta:
http://www.headbands.com/gspot/gspot252dl.html
Open movie with it. It will tell you what codecs was it made with.
Then install/reinstall those codecs, or post this information here.