This could be as simple as restarting your MacBook Pro, or trashing the Preferences files, but it could also require either reinstalling FCPX or even reinstalling OSX.
For that reason, unless someone comes along with a rifle shot solution, I would suggest that you contact Apple Support and let them walk you through it. Apple Support should be free if you have recently bought your Mac, or if you have Apple Care.
You can reach Apple through the "Contact Us" link at the bottom right of this page. You will initially deal with a web page, but you will quickly get to a live person.
another, very generic hint from here:
don't try to be smarter than the boys&girls in Cupertino
• use your Mac as-out-of-the-box: don't optimize, spring-clean, re-arrange preinstalled files
• use Apps as-out-of-the-box: don't re-name, re-locate, don't twist programs
the file-systems of OS and apps are a lil' different to other operating systems; two examples concerning FCPX:
• app should be where the installer installed it - not 'somewhere' on some other drive, or the like
• folders 'Events/Projects' should be where app installs them, on top-level of drive, not somewhere 'hidden' or symLinked, or the like