I've switched to a new computer recently and noticed that when I play a movie and select full screen, the movie will be horizontally off-center (i.e., either above or below where it should be in the middle). I can fix this by going through aspect ration, and selecting original (even if it is already selected).
I've also noticed that this only happens on video's with different sizes. So, if I play a file that is 540x280 and do the aspect ratio fix, the next time I play a 540x280 it will be in the middle on full screen. However, if the next video I play is 620x230 then it will be off-center again when I view in full screen. I hope I have explained this bug properly.
I am using BS version 86.493, WinXP, with an ATI Radeon 9700 with original Dell drivers.
P.S.
Otherwise BS Player is a fantastic video player. The wealth of options, ease of use, small footprint, and on and on are all great.