I tried many times to install the Microsoft Office 2008 update 12.1.0 but each time it would hang.

Finally I found this forum thread about the exact same problem, Msi Wind Forums • View topic – Microsoft Office 2008 update 12.1.0 will not install.

This is how to get the update to install.

Should have an option to edit……thing is it’s to late because your forced quit. Run the installer again and when the installer hangs move the installer window to one side…the error window noted above should be directly behind the installer and thats why you missed it in the first place…the installer has halted (and appears hung) as the error window is awaiting a response from you…..but you dont see it. All you have to do is click the edit button on the error window and then installer will continue…thats it. You can close the error window and the installer will continue.