Machscreen screen designer can be found in its on board that can help you find out if it is assgned to something else in the screen. Intall Machscreen, open your screen, go to view, hotkeys. Make sure it isn't found twice. Not just Ansi code, but the key its self. Make sure it isn't used in combination with a modifier key as well. Also make sure it is be use to imulate any thing in ports/pins, input/outputs.
Brett