Automatic Update install time is not used

Sorry if this is a duplicate, the previous message didn't appear on the
NG by the next day...

Windows Advanced Server 2003: I have automatic updates set to download
and install on the schedule I specify: Saturday nights at 11:00 PM.

This install time that I gave is not being used.

I am looking at two event log entries, one is from source "Automatic
Updates", category Installation, event ID 19, date: 1/14/2005 (Friday),
time 3:47:19 PM (Friday mid-afternoon!), Description: Installation
successful. Windows successfully installed the following three updates:
[then it lists KB890175, KB891711, and KB871250].

The next event log entry is source Automatic Updates, category
Installation, Event ID 22, same date and exact same time (it happened
during the same second, apparently); description is Restart Required: To
complete the installation of the following updates, the computer will be
restarted within five minutes....

And it did restart at 3:52 PM. But WHY do the automatic update install
at 3:47 PM on a Friday afternoon when I have it set to Saturday night at
11:00 PM? Why is it ignoring what I want? What can I check? The
computer date and time is correctly set, and the time zone is Mountain.
All updates have been applied.

I couldn't find any relevant hits on Google or in MSDN; there's so much
discussion of HOW to set the desired scheduled time.

Thanks for any leads.

David Walker