1) Dialogs problem in Default Example: The "Internet Explorer can not display the page" error is not related to the initially reported problem that all toolbar buttons does not work in IE9 in the older version. You could get this error if some monitoring program such as WebSense, Firewall
or a Proxy server
decreases the URL length for example to 1700 symbols which breaks the loading of the editor dialogs. You can see the following help article how to fix this issue: Blank Dialogs Problem
editor.get_dialogOpener()._dialogUrlLengthLimit = 500;
This workaround limits the maximum URL length for the editor dialogs to 500 characters (from the default 2000). This should fix the problem.
http-equiv="X-UA-Compatible" content="IE=8" /> - what exactly is not working: the editor's tools or its dialogs? Note that this is just a workaround and it is recommended to migrate to the latest version.
the Telerik team