Error When Trying to Repair, or Add/Remove Office or Running Setup

When attempting to run a repair on Office
-or-
When attemping to run Add/Remove Programs on Office
-or-
When attempting to Run Setup.exe from Office installation CD

you receive the error message "The installation source for this product is not available. Verify that the source exists and that you can access it."

To resolve this issue, use the Microsoft Windows Installer CleanUp Utility to remove and re-install Office.

Download the Microsoft Windows Installer CleanUp Utility and install it.

Click Start, point to Programs, and then click Windows Install CleanUp.
On the list of installed programs, click each Microsoft Office program, and then click Remove.
Follow the instructions that appear on the screen to complete the removal process.
When the removal process is completed, click Exit.

References:
http://support.microsoft.com/kb/290301/
http://support.microsoft.com/kb/325084