Final Cut X collapses at Yosemite

[Paradiseapple]

Hello friends,
since I updated my Macbook Pro to Yosemite Final Cut X always collapses 2 seconds after opening. I deleted and reinstalled the program twice already - same thing again. Even if I delete the preferences.
On my MacPro all went well after updating to Yosemite.
What do I do wrong?
Its a legal version for sure ...
Thanks in advance
Alfred

 

[Paradiseapple]

Now Final Cut X works because I re-installed and left off my LaCie Thunderbolt external harddisc - as soon as I plug it FCX collapses again.