Could you try disabling the Ajax by setting the EnableAjax=false
of RadAjaxManager/RadAjaxPanel and then check what would be the error on the server? Additionally try enabling script debugging for the browser you are testing with. You could find steps for enabling this option for IE here
. This could point you to the reason for the error.
You can also try removing RadCompression from the web.config of your application and see if it will make any difference.
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