Problem solved, though I would say it's a bug or at least a design flaw.

If your screen size is too small or your font size is too big, then the top frame (which contains the menu) wraps the text on to a line which is not visible in that frame. As the frame doesn't have scrollbars, then there is no way to scroll to the wrapped line and thus the menus are invisible.

Fixed the problem by getting the user to change their font size to small, but would really like a fix to the source if anyone has a suggestion.