As annoying as it is, I do understand that there are literally billions of applications out there that makes it hard for Microsoft to fully test their products with so this point of this post is not to complain but rather hope someone else encountering this problem will quickly find the solution here.
You’re trying to close the Exchange Management Console MMC but notice that you’re prompted with the following error message:
You must close all dialog boxes before you can close Exchange Management Console
You look far and wide beneath the opened windows on your server but can’t find any dialog boxes opened.
The reason why you’re getting this error is because your server has Internet Explorer 9 (IE9) installed. As per the following forum post:
… and this blog:
… the problem isn’t so much IE 9 but rather MMC.
I hope this gets fixed quickly because I can see it being very annoying.