Source : Free On-Line Dictionary of Computing

Helen Keller mode
     
        1. State of a hardware or software system that is deaf, dumb,
        and blind, i.e. accepting no input and generating no output,
        usually due to an infinite loop or some other excursion into
        {deep space}.  (Unfair to the real Helen Keller, whose success
        at learning speech was triumphant.)  See also {go flatline},
        {catatonic}.
     
        2. On {IBM PCs} under {MS-DOS}, refers to a specific failure
        mode in which a screen saver has kicked in over an
        {ill-behaved} application which bypasses the very interrupts
        the screen saver watches for activity.  Your choices are to
        try to get from the program's current state through a
        successful save-and-exit without being able to see what you're
        doing, or to {re-boot} the machine.  This isn't (strictly
        speaking) a crash.
     
        [{Jargon File}]