Did you - upon installation - allow BS.Player to internally
(i.e. for use by BS.Player only; not interfering with your system's codecs/filters) install its preferred codecs/filters?
Maybe you need to install AC3Filter?
Also check (and possibly play with) settings under
(rightclick>) Options > Preferences > Audio > .....
..... "
For AC3 decoding use" (at bottom right)
..... > Output .. "
Output device"
Another possibility is that some connection with quartz.dll is lost.
Then perhaps a re-installation of
DirectX could be the solution.