Maybe try saving the song as a SEQ file first.
File - Save As should offer this option, hard to recall that long ago though.

The next step I would try (if it were me) is, after saving as a seq file, find the 'Make all BB tracks regular tracks'
This would stop RB from trying to generate all the BiaB tracks when you hit Generate.
You would have to select a track or section of a track, and regenerate those manually after that.

Again, this is a pretty old version (2009), so where to find these commands may be in different locations; I am going from memory.
There is a setting in recent RB versions that will cause it to save as a seq file just by hitting save, but back then I think it was a bit more of a manual process.

Of course Chantelle's suggestion is also a good idea, may solve some OS issues like permissions and such.

I do not work here, but the benefits are still awesome
Make your sound your own!