Microsoft Office 2007 upgrade to 2007 setup error encountered.

Microsoft Office 2007 upgrade to 2007 setup error encountered.
Previously I have installed Microsoft Office 2007 in my Microsoft Windows 7 Operating System. When Microsoft Office 2010 arrives, I have upgraded my Office 2007 to Microsoft Office 2010. During the installation process, I encountered setup errors saying my product installation is corrupted.
My installation disk is the original copy from Microsoft and I believed that was not counterfeited because I bought it from a reliable store which is a Microsoft partner in our area. So there’s no room for doubt that my copy is counterfeited. Here’s the error message.

Setup Errors
This product installation has been corrupted. Run setup again from the CD,DVD,
or other original installation source.
OK
