This update doesn't appear to like Exchange 2007 or 2010
It prevents access to the EMC either on the server of remotely, and also other MMC's including the Event Viewer
I had a similar problem to this. I am running Windows Server 2008 Std with Exchange 20007. Windows downloaded an update (KB2449742) for Exchange 2010 and applied it to our Exchange 2007. Caused a break in the entire web platform (no OWA, email connection on mobile phones, and couldn't even open the event viewer because it affected the MMC). Once I uninstalled that update and rebooted, everything was back to norm.
Removal and reboot works..