This sort of issue occurs in many systems so I narrate to a nice audio recorder then I can use those audio clips to add to the tracks in the editors.
I am not offering to write a tutorial but to share a common solution I use.
I created a photo/video project and had dictated half of the narration when iMovie 11 refused to take any more narration. Apple told me there was probably a flaw in the program and had no solution other my starting over.
But I was wondering if anyone knew of a way I could transfer all the photo/video portion to a new project so that I didn't have to redo that part of the project.
I am working on an iMac, snow leopard, and iMovie 11.
Any help is appreciated.