The RadControls for ASP.NET AJAX
are not supported in IE Quirks mode as you can see on our web site
. We support IE6 and above while the quirks mode is almost equivalent to IE5.5.
The following forum thread may be helpful for you to prevent running the Internet Explorer in quirks mode: http://stackoverflow.com/questions/646742/how-to-programmatically-turn-off-quirks-mode-in-ie8-webbrowser-control
the Telerik team
If you want to get updates on new releases, tips and tricks and sneak peeks at our product labs directly from the developers working on the RadControls for ASP.NET AJAX, subscribe to their blog feed