IMovie won't import videos .mov file?

I've been trying to import videos from my Finder (on the mac) to the imovie program I have for the past two hours. Every time I try import them, it shows a "Optimizing Video" thing and then completely quits...no warning, no "not compatible"...it just stops and doesn't continue. I have iMovie '09. I've also tried importing them through iPhoto (it's worked in the past) then importing it to iMovie. Last time I used iMovie was about two months ago and it worked just fine.....What's wrong with my iMovie??