Once again:
it is definitely true that MegaPak should not give any error and it is supposed to show only styles / real tracks that are included!Some of these errors where fixed with build 294.
Another some of these errors only occur when manually installing the Realtrack Updates.
So, in order to fix it, delete BIAB-Folder (C:\BB), re-install everything except RT updates, apply the 294 patch and delete =clap_be.sty (which is not meant to be included with MegaPak but accidently got there.)
And don't get confused by this "buy ultrapak propaganda" that seems to be very typical for this message board
(I'm not saying UltraPak is a bad buy. It definitely isn't and I finally upgraded from MegaPak solely for the additional Jazz Realtracks.....

)