Log in screen dies

[Mike McMullin]

  A couple of times I've noticed this oddment on 10.04 32-bit, User -A- will 
be logged in, and the the screen will be locked, User -B- will log in, and 
later User -A- goes back switches to their account, and logs out, User -B- 
reactivates their login and when done logs out.  At this point the Login GUI 
is gone and you are seeing vestiges of what went on during the boot process.
<CTL>-<ALT>-<DEL> causes shutdown, <CTL>-<ALT>-<BKSP> does nada.