Actext.dll add-in error opening Outlook

I upgraded a PC from 98 to XP Pro. It has Office XP on it and when I open Outlook i get the following error message:

The add-in “C:\Windows\System\ActExt.dll” could not be installed or loaded. This problem may be resolved by using Detect and Repair on the Help Menu. Unable to load “C:\Windows\System\ActExt.dll”. You may be out of memory, out of system resource, or missing a .dll file.

It has 128 MB ram, its a Celeron 1.3 ghz. I’ve tried to re-install outlook, re-intall office, done detect and repair and also un-installed and re-installed Norton Anti-Virus 2003, but nothing will get rid of this error.

Once the error comes up you can press ok and continue to use outlook as normal (or so it seems) but it’s an extremly annoying message.

Please help!