I also solved my issue the same way as described.
In iMovie:
File -> Update Projects and Events
For me, one of my projects crashed iMovie, so I was seeing nothing. I watched the events that it was importing, and then moved the one it had tried to import before it crashed (I moved it to my desktop).
Then, I ran Update Projects and Events again, and everything went through fine.
So, if you're having problems, just look for the event that is causing the crash, move it out of the iMovie Events folder, and keep trying. Repeat for each event that is causing a crash.
(As a side note I was able to import that event after when it was the only event in iMovie Events).