IMovie Won't Import or Create New Project - Only on Guest User.

Yesterday while working on an iMovie project, my computer crashed. And after I reopened the iMovie application, something is wrong. My projects shows with red color in both the video and audio files. I read somewhere that I have to import the files into iMovie for it to work again. The problem is I can't import. When chosen a file, the import button doesn't respond. I can't create a new project either. It says 'The act could not be done' (or something like that - my computer is in danish )

There is a yellow triangle with an exclamation point on the project.

I tried logging into a different user on the computer, and then there is no problem.

I run OS X 10.9.5

I really hope someone can help me.

Thanks in advance