Microsoft Office 2010 fails to launch on existing user profiles after product key change

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http://serverfault.com – I have a client with a small business network on a domain of around 10 computers, and Microsoft Office Professional Plus 2010 has been installed on them for a couple months and working fine. Just recently, I needed to change the software key [we received a different key for an updated volume license agreement, exact same product], so I logged in to each machine as an Administrator and used the handy option to "Change Product Key" within the help menu of any Microsoft Office application. Afterwords, I could launch Microsoft Office applications with no problem. As users logged in to their (HowTos)