I am having the same problem but I only own one camera, so I don’t think switching cards between multiple cameras is the problem. I have been searching the internet to see if anyone else was having this problem, I STILL HAVE N OT FOUND A SOLUTION.
What I have been doing is importing on my Macbook pro that has FCP 5.1 and then copying the files to my desktop which is Studio 2. It has been a big pain. dubbling my start up time.
If you find any answers I would definately appreciate any solutions. Thanks