Windows Installer is used to install and maintain your software
installations. If Office is attempting to install on demand Windows
Installer is utilized. Windows Installer error 1634 is a generic
error. It simply means "component not used on this machine".
It could be there was still some code looking for your Cordial 2005
add-in and it could not be found or Word was attempting to install
something.
I suspect the former since a repair/reinstall didn't correct the
error. If you also deleted files/folders, etc then you probably
deleted whatever was looking for the add-in. It could have been the
add-in placed macros in your Normal.dot and it isn't recreated during
a repair/reinstall.
In any case I'm glad to hear you have it resolved.