Can't update office 2003 - opuc4.cab Unknown Publisher

Hello, I just re-installed office 2003 on another XP pro machine and when I
try to update office I get the following message after allowing the ActiveX
control to install. (Windows has blocked this software because it can't
verify the Publisher)
Name: opuc4.cab
Publisher: Unknown Publisher

The site is trusted I have turned off windows defender and the firewall but
can't get past this security warning.

Anyone know why ths is happening?

Thanks,