If you're having problems with dialog boxes not displaying or closing properly, you will need to turn on IE 9 compatibility mode.
Click on the "enable compatibility mode" icon which is just next to URL as shown below. When using compatibility mode, the icon will turn blue. Otherwise, when compatibility mode is not enabled, the icon will remain white.
IE9 Compatibility Not Enabled:
IE9 Compatibility Enabled:
Note: if you do not see this icon, you will need to navigate to a different page. The icon only shows on pages that show up differently in IE 9 and in older versions of IE.