After much trial & error this fixed the problem:
Run the Windows Installer CleanUp utility to remove the Windows Installer registry settings, and then reinstall Office.
To do this, follow these steps:
1. Download, install, and then run the Windows Installer CleanUp utility to remove the Windows Installer registry settings that are associated with your Office installation. The following file is available for download from the Microsoft Download Center:
msicuu2.exe
(or find the link at http://support.microsoft.com/default.aspx?scid=kb;en-us;Q295823 )
To use the Windows CleanUp utility, follow these steps:
a. Click Start, point to Programs, and then click Windows Install Clean Up.
b. Select the program that you want to remove, and then click Remove.
c. Click OK, and then click Exit.
Then reinstall Office.
Hoorah! :D