[Cube] Cube won't shut down

[Bumala, Robert W]

Hi all,
  I've been having an annoying problem for some time, and I wonder if
you can give some insights as to where to look for it.  When the cube is
commanded to shut down, such as with the pull down menu, or for a
software update, the cube hangs forever.  There is no keyboard input,
nor mouse movement.  When I use to power switch to force it to shut down
it does, and then restarts fine.  It seems to me the problem is in a
shutdown script.  

Does anyone know where this script is located? 

Thanks,
Bob.