I'm running Ubuntu 12.04 as a VirtualBox guest with a PC keyboard, and whenever I press Alt, the menus for the currently focused application appear. While holding Alt, if I press other keys, sometimes the menus open. I never want this. There are no cases when I ever activate menu items from the keyboard. Is there a way to permanently and completely turn this off, so that no menu can ever appear or open in response to any key press?
It seems like this question must have been asked a million times, but I have searched and searched and can't seem to find any answer. I have already turned off the dashboard, but now I need to unplug any and all menus from my Alt key, so that I may use it.