IMovie update 7.1.2 crashes at start while generating thumbnails

Question

Since I updated iMovie to v7.1.2 it crashes every time I open it. First shows a message saying that a camera has been detected (although there is no camera connected) Then it starts generating thumbnails and crashes.
I re-installed version 7.1.1 and works wonderfully

Answer 1

After a very patient work I could make my iMovie work.
When the iMovie 7.1.4 update starts (7.1.2 had the same issue) it checks your HD (and all other storage devices you may have connected) for video files. This is different from version 7.1.1. If during the check, for any reason, cannot access a file, it crashes.
In my case I had to check permissions for every video file and/or folder containing them until I solved the problem. Fixing permissions with Disk Utility or changing permissions for a folder and all enclosed subfolders, it is not enough. You have to check each individual file. Not very difficult but time consuming.
Now iMovie is working fine. I really regret that Apple made a change in the two last updates without any warning. After all the turmoil provoked in this and in other related forums by desperate iMovie users experiencing this problem, they should have acknowledged the issue. By the way. it started last June. I would have expected that they publish some suggestions in their support website.
I spent almost 4 hours doing what finally was the answer to the problem. Not to mention the timeless trials I made during the last months.