LOL! :roll:
This is a very interesting bug, but i believe that can be traced down very easily. BSplayer just simply "think", that displaying into another resolution - thats all
The resolution is obivously bigger, so, you see only a part of it.
Solution? Uninstall and completely REMOVE BSplay registers (ques why bts including a util to do it there...) - and install again.
It might be even better to reinstall Windows from scratch, but you probably dont even want to heat that, right? :?
So, another thing that can be done to solve this easily is - select a resolution for fullscreen playback. For example 800x600 (jsut something diferent - or even the same res you using for desktop) - and try, what happens
Good luck.