iM6 - some transitions have wrong soundtrack?

Hello,

I have been using iMovie 6 for sometime, and I feel pretty comfortable with it, but something has started happening on my latest movie that has never happened before, and I don't know how to fix it? All of the transitions in the beginning of the 61 minute movie are fine, but during the last 20 minutes or so, the transitions all contain the same audio (which is a short segment from one of the earlier clips)? I thought it was just one clip, and of course I could work-around it by simply dropping the volume on the transition, but I started checking, and almost all of the later clips shared the identical (and incorrect) "soundtrack".

Has anyone ever had this happen? Does anyone know how to fix it?

Thanks,

Lincoln