Update 12/13/2011: Please note that starting with today, you do not need to call Microsoft Support to get the fix to resolve this issue. All that is required now is installation of December 13, 2011 IE security update, KB 2618444. The below blog post has been updated accordingly.
We are happy to report that a fix for the Exchange Management Console (EMC) issues when Internet Explorer 9 is installed is now available. To be specific, we have talked about this in a previous blog post:
Exchange 2007 or 2010 EMC might fail to close with "You must close all dialog boxes before you can close Exchange Management Console"
How does this fix need to be applied?
In order to install the fix, a released version of IE9 needs to be installed on the machine first. Then:
The KB article talking about all this has also been updated: KB 2624899 FIX: You cannot close the EMC window on a computer that has Internet Explorer 9 installed
Finally, I would like to thank the Internet Explorer team for working with us on this interoperability issue and producing this hotfix.