Recently I installed Office 2010 and was pleasantly surprised at how everything worked and how easy it migrated. Then one day I went to open Outlook it started crashing unexpectedly, I found the following article which works for some people but did not work for me.
During my process of getting it backup and working, I had to do the following
Before looking online
I performed a repair/reinstall
Perform the steps from the article above
Disabled the Add-In from the Options tab
Created a new profile and setup e-mail account again
Mail worked and the add-in was gone
For another user we actually had to removed 2010 and install 2007 then reconfigure the e-mail accounts again.
After that we were able upgrade 2010 and restore functionality for them.