Can anyone have a solution for this issue
Microsoft JScript runtime error: AjaxControlToolkit requires ASP.NET Ajax 4.0 scripts. Ensure the correct version of the scripts are referenced. If you are using an ASP.NET ScriptManager, switch to the ToolkitScriptManager in AjaxControlToolkit.dll.
I am using asp.net 3.5, VS 2008. The version i can see in the AjaxControlToolKit.dll file 3.5.40412.2.
Check if this link helps you resolve your issue -
http://blog.thinkoriginally.com/2010/05/03/microsoft-jscript-runtime-error-ajaxcontroltoolkit-requires-asp-net-ajax-4-0-scripts/
EDIT: Check this link for dll load error resolution -
http://geekswithblogs.net/LessonsLearned/archive/2008/08/21/hidden-surprises-in-.net-3.5-service-pack-1.aspx
I Think you have problem with your VS 2008 version. Because Ajax 3.5 dll requires minimum Visual studio service pack 1. But you may not have service pack 1. so please install it.
Before installing service pack 1 remove Ajax toolkit from toolbar and when installation complete again add it and run. I was also having the same problem and I have solved in this way.