Obvious question that has to be asked: you bought FCP X from the app store, right?
Given that we're talking legit: the only difference a Hack would make in running FCP X (and any Pro app) that I know of, is that your graphics card must be working 100% full CI/QE/OCL.
If not- no pro apps. That includes audio-only like Logic. So make sure your graphics are working correctly.