Hi,
Are you able to open the site from another browser: IE, Firefox, Chrome, Opera? You can also try to load it from another machine outside of your current network and see whether the problem is not network, antivirus or proxy related.
Best regards,
Rumen
the Telerik team
Consider using RadControls for ASP.NET AJAX (built on top of the ASP.NET AJAX framework) as a replacement for the Telerik ASP.NET Classic controls, See the product support lifecycle here.