The Exchange Product Group has made a public statement that the issue with EMC & IE9 (read here) has been resolved and a hotfix is available from Microsoft Support. I really don’t understand why the fix is not available for public download. The issue was that you get prompted to close all windows (as shown below) while trying to close the EMC, even when there are no open windows.
In order to install the fix, a released version of IE9 needs to be installed on the machine first. Then:
- MS11-081: Cumulative Security Update for Internet Explorer: October 11, 2011 needs to be installed. This can be obtained from Windows Update or – if you need to download it for local network installation, the packages can be obtained here. The installation of this package is REQUIRED for proper operation of the EMC hotfix.
- In order to obtain the actual hotfix that resolves the interoperability problem with EMC, you will need to call Microsoft support and request a hotfix. The hotfix package is currently not available for public download, but can be obtained from support engineers, who can get it from internal hotfix servers. When you talk to support, the hotfix that you need to request is for the KB 2624899. Please note that this article is not publicly available at this time either.
More info @ source