I logged out of Windows and back in and I couldn't find Norton in the System Tray in Windows XP SP3. I opened the task list and only one copy of ccsvchst.exe was running (the System user copy). I tried to manually run Norton from the start menu and that didn't work. Finally I ran the autofix support tool and it told me there was a pending install and I needed to restart.
Apparently 20.3.1.22 was installed and waiting to run and when I logged out and back in the user process tried to load version 20.3.1.22, but the system process was still running 20.3.0.36, so the user process failed to run.
There should be some kind of smarts about this as to what happens if the user logs into Windows with an update pending to prevent Norton from not loading at all.