If you are using IE 8 or later and see the warning, "Unsupported Browser Version", make sure your browser is not running in Compatibility View mode.
You can tell whether your browser is running in Compatibility View mode by looking for the Compatibility View icon inside the URL field at its right end, as shown below:
If the icon is colored (blue), Compatibility View is enabled. If it is gray, it is disabled.
You can disable Compatibility View by clicking the icon, or you can choose Compatibility View from the Tools menu (when the option has a check next to it, choosing the option disables it).
If the icon is missing from the URL field, then choose Compatibility View Settings from the Tools menu and clear the Display intranet sites in Compatibility View checkbox.