Remap Control+Command+F from Facebook to Full Screen
I had this problem too.  Turns out the PandaBar app was to blame.  It had overridden the Control-Command-F keyboard shortcut for posting to Facebook what I was listening to.

Go into PandaBar Preferences -> Shortcuts and change or clear the "Post to Facebook" shortcut.

Then the full screen shortcut will work as expected in all your other apps, without having to override it with System Preferences changes.