Try Deleting Your Preferences First. Then post here if you still have the problem. I have broken this rule a few times, but thought it would be useful to have up here. If you don't know how, at least in a Mac you have to go to your X-Plane folder (In finder, not under Devices), Output, Preferences. Edit: Deleting doesn't actually require dragging them to Trash, it just means taking them out of your XP folder. You can then see if that fixed the problem, if it does, then actually delete your prefs. If it doesn't, put your prefs back in the correct folder and ask for help here or elsewhere.