HELP! Error message about compress size mismatch

Hi there, I received an error message from 360 that it couldn't save my file after I'd imported it and been working on it for awhile. And of course, there's a deadline involved in less than 4 hours...  here's the background info:

Current state: One large 150 slide file in 360 with 2 scenes.  Unable to save.

First scene was course content (first half of it) created by me in Powerpoint 10, then imported into Storyline 2 by someone who worked on it, then zipped and given back to me.  I then imported it into 360. After that I imported the rest of the course content (info below) into the same course as the second scene.

Second scene comes from the second half of the course content I created in Powerpoint 10, worked on it and imported it into 360 where I added it as the second scene to the first scene mentioned above.

Now I'm trying to save it, and it's not saving.  I thought it saved before when I first imported it all but I can't remember.  Thanks for any helpful advice!