Adam Miller wrote:
Also, won't Ctrl+Alt+<Fn> still work to get you to a vt where you can at your choice kill X manually, or try to debug the problem further?
    

Yes, yes it will. Solid observation :)

-Adam
  
NO!  If the X server is in a tight loop sometimes you cannot even get a login prompt at a terminal.  The ONLY thing that works is Ctrl-Alt-Backspace.  And sometimes you have to issue it a few times and wait but generally it will kill the X server even when you cannot get logged in from a terminal.

Regards,
Gerry