Windows Updates seem to download but they don't Install.

I have a group of computers that I am trying to run WAU on. I have set
this up in group policy - Download and schedule install. Nothing seems
to update. None of the computers have gotten SP2. In the windowsupdate
log I see lots of activity and it looks like it has downloaded some
updates. At the time the updates are supposed to install 3:00 I see
Forced install timer expired for scheduled install. If I log on the
the computer as administrator i see the winupdate icon and it tells me
that there are updates ready to install so I know it is downloading
the updates. I can install them as admin. If I log on as a regular
user I don't get the option to install the updates.

Also, I went ahead and installed SP2 on on of the computers when
logged on as administrator. Since then no updates have been
automatically installed.

Does anyone have any Ideas?

Thanks.