Originally Posted by chumawumba
So lately when I try to use FCP X on my 2012 MBA 128/8/i5, I get Quicktime Error 50, and I've tried alot of things like deleting render files, but nothing seems to work. If I delete FCP X (I don't mind losing old projects.) and re install it, will everything be back to normal?
I'd suggest first moving all your projects and events to another folder. Just rename your folders "~/Movies/Final Cut Events" and "~/Movies/Final Cut Projects" to something else (e.g. attach .tmp in the end...). If FCPX then opens without problems, something is broken in your projects. You can move them back one by one to see which one is causing the problem.
If it still doesn't open, you can delete and reinstall FCPX. If it works after that, you will not have lost any of your projects, since you just backed them up in a different folder. If it still doesn't work (clean install without any projects), then I would contact Apple.