IMovie crashes when adding audio clip

Question

I am in the middle of creating a movie, everything has been going very smoothly and then suddenly iMovie started crashing whenever I try to add a sound clip to a slide.
The audio clip does initially appear to be added, but then iMovie hangs and I have to force quit.
Any ideas on why this would suddenly start occuring when everything was working fine up 'til now?

Answer 1

I hope you don't mind my jumping in and adding to the muddied waters, but I am also having trouble with iMovie transitions. I just bought the MacBook Pro - 200 gig hard drive with boosted RAM. I have experienced the following problems:
1. After reading Karl's caution about iMovie trash, I don't empty the trash until the project is completed, so that's not the issue.
2. And this is what's odd . . . I just put one movie together and had not a single glitch. I pulled stills in using Ken Burns, was able to go back and edit the clips, change transitions, etc.
3. I have another movie that I have been working on and it was going fine UNTIL I added the first transition. After that, whenever I select a clip I get a black screen and have to reimport the photo to see it.
4. When I try and add transitions, sometimes they work, sometimes nothing happens, sometimes the system crashes, and sometimes it looks like it is going to render, but the rendering line never progresses.
5. I have tried deleting the plist files for both iMovie and iPhoto, and repairing permissions, but it doesn't work.
6. No security features are turned on.
7. I do have slick transitions, but as I said, they worked fine in the first movie (where trash was never emptied.)
This is making me crazy and is far too time consuming. Karl, any thoughts?
Thanks so much.