(1) Is the following thread maybe somewhat similar to your problem?
http://forum.bsplayer.com/subtitles/...html#post49041
Then I would also ask you to download/install and try the latest version first (
click here). Before doing so, please read
(3) first.
(2) Do you have this problem irrespective of the type of the video-file?
(I ask that as
tadmaz's post specifically concerned mkv-video-files using DXVA and it doesn't - in fact - concern subtitles, so I don't understand why you're referring to it. Also he was running XP SP3, whereas you're running Vista SP2!)
(3) When you installed BS.Player, did you allow it (when it asked so) to also
internally install its preferred codecs/filters?
(
Internally meaning for use by BS.Player only and not interfering with your system's codecs/filters.)
If you didn't before, please do now.