Microsoft released the official fix for: You cannot close the EMC window on a computer that has Internet Explorer 9 installed. Windows Internet Explorer 9 installed, you start the Exchange Management Console (EMC). After you make a change and then try to close the EMC window, the window does not close. Additionally you receive the following message:
You must close all dialog boxes before you can close Exchange Management Console.
Download: KB2618444 Cumulative Security Update for Internet Explorer: December 13, 2011