You are the first to report such a problem. Please make sure that you are using the latest version of the RadControls for ASP.NET AJAX suite, with version number 2008.1.415.20. In case you can reproduce the problem with the latest version, please prepare and send us a simple running project, with which we can reproduce it on our side and a video, showing the steps we need to follow in order to reproduce it. Could you additionally tell us which browser (and version) you are using?
the Telerik team