In general there are things that you can do when Final Cut Pro crashes on startup or unexpectedly quits during edit or when shutting down Final Cut Pro.
The current wisdom is to “Trash the Preferences” (Shades of OS 9?)
Yes, there are still things like Extensions and Preferences lurking in OS X that you thought were left behind in OS 9 and they can cause issues just the same. Only this time they are not in one neat place to find. There are articles on the web that address this issue.
OR you can download the neat little OS X utility that does it for you.
FCP Rescue is an AppleScript utility that takes care of doing all those things in the proper order and restores your files as they were.
The next step toward resolving your problem is; does it work with another user login?
Open System Preferences>Accounts and create a New User (Test) and (1234) for a password. Once the account is created, you logout of the current user and login to Test. Try the same operation to see if the same problem still exists or is resolved. If the problem is resolved then it definitely is a user account issue and not an operating system issue.
If severe problems still exist it may be necessary to reinstall Final Cut Pro and it’s associated applications. Properly deleting Final Cut is key to getting a good reinstall.
To uninstall Final Cut Pro 4.5:
To uninstall Final Cut Pro 4:
To uninstall Final Cut Pro 3:
If this fails to resolve your problem(s) with Final Cut Pro - It may be time to reinstall the operating system to insure proper operation of your NLE workstation.