The 2007 Microsoft Office system does not support upgrading from a prerelease version of the 2007 Microsoft Office system
I've just come across this when trying to install Office
2007. The Office 2007 readme says this is a known issue due to having Office Web
Components (OWC) installed. I have scoured by system for installs of OWC and
removed all of them and still I get the problem.
I did a google when I got back home and found a blog entry by Scott Hansleman
http://www.hanselman.com/blog/Office2007WontUpgradeFromAPrereleaseVersionOfThe2007OfficeSystemOffice2007SetupSpelunking.aspx
He got round it by using MyUnInst from Nirsoft but the later mentioned Expression
Beta.
Well I had Expression Beta installed and went for that and Office is now
happily installing.
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