See http://support.microsoft.com/?kbid=836178 "You receive an 'invalid
product key' error message when you start an Office 2003 program after
you install Office Professional Edition 2003" and http://support.microsoft.com/?kbid=842566 "'This is an invalid CD Key
value' error message when you try to install Microsoft Office" for some
possible solutions. More information from you would be helpful though.
