Automatic update can bring computer out of hibernate?

I'll try this again.

I found my wife's Windows XP desktop powered up yesterday morning. She had
placed it in hibernate just before midnight the night before. I searched
around and found that the WindowsUpdate.Log file that had been modified in
the wee hours. If I am interpreting this correctly it seems automatic update
(AU) took the computer out of hibernation at 1:00 AM and then something did
(or did not) happen at 3:00 AM. The machine then stayed on. I looked at
Control Panel|Automatic Updates and sure enough it was set for automatic
download at 3:00 AM (I think this was set up during Windows XP
installation).

Question: Is Windows Update supposed to turn the computer on for any reason?
I thought that during hibernate NOTHING was running -- and certainly not the
CPU checking the time. Is this happening via the NIC?

I'll obviously take updates out of automatic.

Here are the pertinent log entries:

2005-09-11 23:56:18 684 5bc AU
AU found 0 updates for install at shutdown

2005-09-11 23:56:18 1064 438 Misc
=========== Logging initialized (build: 5.8.0.2469, tz: -0700)=====

2005-09-11 23:56:18 1064 438 Misc
= Process: C:\WINDOWS\Explorer.EXE

2005-09-11 23:56:18 1064 438 Misc
= Module: C:\WINDOWS\system32\wuaueng.dll

2005-09-11 23:56:18 1064 438 Shutdwn
Install at shutdown: no updates to install

2005-09-11 23:56:22 684 124 AU
AU received hibernate event

2005-09-12 01:00:38 684 124 AU
AU received wakeup event

2005-09-12 01:00:39 684 124 AU
AU received wakeup event

2005-09-12 03:00:10 684 124 AU Forced
install timer expired for scheduled install