mumble mode

from The Free On-line Dictionary of Computing (8 July 2008)

mumble mode

   <jargon> The mode a program, piece of hardware, or other
   system is said to be in when it is still running and perhaps
   reacting to input and/or occasionally producing output
   (especially if it shouldn't), but in a way that appears wildly
   inappropriate to the task it is supposed to perform.

   Compare "{off the trolley}" and "{deep space}".

   (1997-03-27)