Corrupt file, created with beta 1 and beta 2 edited (Mac OSX)

Well, yes, the error message tells you where the problem is so you can fix it :-). The problem, as you see if you click Show Details, is the content of staves 1 & 3, which are actually hidden. They have measure rests, but the ones in the shortened measures have the wrong length.

Probably the sanity check code could ignore or even fix these. Meanwhile, though, you can fix the score by unhiding empty staves, selecting the contents of staff 1, hitting delete, then doing the same for staff 3. Resave and no more complaints.

I can't find a way to reproduce this particular corruption in a score created from scratch in the RC. I tried hiding empty staves and then changing a measure length, but the measure rests were always correctly shortened.

So my sense is, RC is acting exactly as it is designed to here - telling you about the corruption so you can fix it, and it does not seem it would create the same corruption.

If you can remember how you created this and re-create the same situation in the RC, we'd want to know about that.