It seems like all of your errors are coming from divs that you have given an ID of "Radwindow_____", so it does not look like there is any issue with Telerik's RadControls here. I visited your site and everything seems to be working just fine. I believe this is an error stemming from the layout defined in the top of your page (lines 250 - 700) and not from the telerik objects defined at the bottom of your page (line 750 - 900).