This sort of thing can happen with a Gamepad controller plugged in. Sometimes the 'Dead-zone' isn't configured correctly. I am sure the Character controller code I used had joystick features that I just completely ignored because I didn't have any plugged in myself. If instead you had no controller plugged in, potentially some other device is sending that signal. I'm really not sure what else that could be. Sorry about that experience... it would be nice to just build a game and have it work everywhere!!!