Here is a tip on how to delete the Plist (preferences).
It is possible to have a corrupted clip. It is also possible to have corrupted cache. It could also be that you need to reinstall iMovie or OSX or both.
To see if it is preferences, you could try opening iMovie in another user account on your Mac. If it opens, you know it is something specific to your user account - either preferences or a corruption of some kind.
One way to test this is to temporarily move your events to the desktop. See if iMovie will start. If it will, add the Events back to the Movies/iMovie Events folder one at a time. Then restart iMovie each time. When it crashes, you know that event is corrupted. If the event is corrupted, you can try deleting all the folders within the Event that are called Cache, Thumbnails, or Stabilization. Take care not to delete the clips that are not in a folder. Then restart iMovie. If it is not bad cache but a bad clip, you can remove the clips from the event and add them back one at a time, restarting iMovie each time.
You can test projects for corruption in a similar way.
If you have Apple Care on your Mac, then you can call Apple and they will walk you through all this. If not, they may charge you (maybe not since you just bought iMovie 11)