Problem when auto download and install updates

Hi,

I have set the group policy to option 4 to auto download new patches
and install at a specific time.

On the client PC, have an entry in the System log saying

Event ID:18
This computer is currently scheduled to install these updates on Friday, 3
February, 2006 at 16:00:
- Security Update for Outlook Express 6 Service Pack 1 (KB897715)

But the patch isn't install after 16:00 when user is logged in.
I thought the patch will be installed but pop-up a message window to notify
the logged in user to restart the PC
to complete the installation.

I have also disabled the No auto restart PC policy setting.
Anything I have missed ?
TIA

Steven