OK, that's a lot clearer, thanks. It's still quite a puzzle.

Off-the-wall guess: did you by any chance leave the computer and BIAB running for the whole week during the repeated plays for rehearsals and then performance? A Windows out-of-resources problem?

As for the muted piano track, can you repeat the problem by doing that? I don't think it would matter, either, but when tracking down bugs, anything out of the ordinary could be a clue for when you talk with PG Music Support.

Is it possible you have used RealTracks in your version 2012 that she doesn't have in 2011? Also, I think by version 2011, BIAB was using the newer format of RealTracks, but that's something to verify with Support. At one point around there, newer format tracks would not work with the older version. [None of this has to do with your slowdown problem, just the problem of transferring songs to her computer.]

BIAB 2025 Win Audiophile. Software: Studio One 7 Pro, Swam horns, Acoustica-7, Notion 6, Song Master Pro, Win 11 Home. Hardware: Intel i9, 32 Gb; Roland Integra-7, Presonus 192 & Faderport 8, Royer 121, Adam Sub8 & Neumann 120 monitors.