Can you please verify that you granted permissions for all users to operate with the Telerik.Web.UI.WebResource.axd handler? How to do that you can see from the relevant paragraph of this article
in the product documentation.
You may also try replacing temporary RadScriptManager with asp ScriptManager or set its EnableScriptsCombine
property to false to compare the results. Additionally, make sure you use the latest version 2010.2.713 of the suite.
the Telerik team
Do you want to have your say when we set our development plans? Do you want to know when a feature you care about is added or when a bug fixed? Explore the Telerik Public Issue Tracking
system and vote to affect the priority of the items