You could always re-run BS.Players own codec manager (codecmanager.exe) which always automatically runs at BS.Player's installation. You can find it inside BS.Player's installation folder (default: C:\Program Files\Webteh\BSplayer
Pro).
If that doesn't help, well .... there is this forum to ask so that your fellow users may be able to help you. (Buyers of the Pro-version are also entitled to receive direct e-mail support from BS.Player's team itself.)
In order to enable your fellow users to help you, always make sure to provide the necessary info (
like with what codec the 'troublesome' movie was encoded upon its creation).
In this connection please read the first few items of my Help2Help-post (which perhaps isn't entirely up-to-date anymore, but still holds plentyfull usefull information).