It's now april 2014 and the problem is still there, deeply embedded in the bsplayer core.
Bsplayer is not displaying subtitles not only after a resumed Windows session, but every time I play some game in full screen.
I'm the kind of user who likes to watch a movie in many reprises. The bsplayer remains all day long in background but when becomes the active application... it looses its focus... too many times... :)