What makes iMovie 11 crash when exporting a project? I'm making a short movie with iMovie.

From time to time (more than once per day) I export it in medium format.

I did it with my last version, then I refined the video and when exporting again iMovie started crashing.

After lot of hacking, reading (this great post for instance, which gives multiple very useful solutions), I understood that the cause was some corrupted video. 

I crashes probably in the part where I included some video produced with iMovie itself. So, I create a temp project with iMovie, and I export it to use the exported video in my MAIN project.

I removed it and now it works. If I include it again it sometimes crashes, and it is the weird thing:
I never changed this video, and when I include it again some time the project is exporting well, sometimes not (it seems a not-reproducible issue! crazy!).

Hence I have the following questions:


is it possible to 'repair' the video which make the project crash?
is there a way to understand, from the error report, WHICH WAS THE PART CAUSING THE CRASH?
iMovie is great but I think it is still somewaht a toy. So if I buy final cut pro x, can I import iMovie videos without getting crazy?


-- UPDATE --

The followings are not  possible solutions:


Removing the "organic" title (I'm not using it)
clean the preferences entry in the library folder (com.apple.iMovieApp.plist), I've already tried it
You can try to convert the defunct video to a different codec. Use something Lossless like ProRes, if you can, or Motion JPEG. Then put the clip back into your project. 

I had this problem once in FCP7 for about a week. It didn't go away until I re-recorded that video (which was painful, but in my case, doable). I wouldn't suggest such a radical solution in your case though. There's a lot you can still try. Read the linked post. Basically what I did was: "circumvent or force media conversion at different production stages".

You can also open Console and take a look at the log when the app is crashing. That normally gives hints what is going on in the background.