Photo Story keeps crashing

I am working on a project in photo story 3. I have the allowed limit of 300 photos and when I input the music it was all jumpy (like a scratched record). I deleted all the music and re-selected it and it appeared to work, but then when I re-selected the third song the the whole thing crashed and I lost all my changes. what is going on?? I used it before, with not so many pictures, and it's always worked well.