re: autoupdates setting = 'download and let me choose' or ' notify me '.

A while back I started seeing this " Install updates and shutdown"
message as a choice on autoupdate PC's with a classic view shutdown
screen. Anyone know exactly WHEN this started ? AND - my real reason
for asking: How does someone logging onto an XP Home machine with no
password enabled ( so sees no log on nor shutdown box) get notified with
the same message ?

I was at a small shop yesterday and he had 'notify me' selected and "a
while ago' his system started hanging at shutdown rather than turning
off the PC. I was wondering if maybe some bit is set somewhere trying to
prompt him to install the updates. I rebooted and selected "do
nothing" for autoupdates and it then shutdown OK.Tried it a few times-
ok. Enabled it and hung again - have to hold power button to turn it
off. Event viewer shows no errors for system nor apps.

I was then thinking back to simliar 'not powering off issues ' for which
the fix was to use the hive update program to have it close any
outstanding jobs and wondering if THAT fix was maybe related to these
'pending update issues' - some 'still running app' thats hanging around
from when "it first needed an update and didn't do it"?

Any ideas as to why enabling autoupdates coincides with not powering off
?