After installing Internet Explorer 9 onto an Exchange server, you may have experienced that the Exchange Management Console (EMC) will not close. The following error is observed:
You must close all dialog boxes before you can close Exchange Management Console
This did not affect everyone, and you may have been blissfully unaware of this
The Exchange Team Blog originally discussed the issue, and then posted details of a fix.
For even more good news, now you do not need to call into support to get the update, and the following cumulative update for IE should be installed to remediate the issue:
MS11-099: Cumulative Security Update for Internet Explorer: December 13, 2011