New Post: Server Error in '/' Application. An item with the same key has already been added.

Hi, I have latest BugNet. It was working fine but from few days I started receiving error.
Error text is given below. If I refresh page it started working. How to fix this issue.

Thanks

/Error**********/
Server Error in '/' Application.

An item with the same key has already been added.

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.ArgumentException: An item with the same key has already been added.

Source Error:

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Stack Trace:

[ArgumentException: An item with the same key has already been added.]
System.ThrowHelper.ThrowArgumentException(ExceptionResource resource) +52
System.Collections.Generic.Dictionary2.Insert(TKey key, TValue value, Boolean add) +10925834
AjaxControlToolkit.ToolkitScriptManagerHelper.GetAssembly(String name) +67
AjaxControlToolkit.ToolkitScriptManagerCombiner.IsScriptCombinable(ScriptEntry scriptEntry, Boolean enableCdn) +27
AjaxControlToolkit.ToolkitScriptManagerCombiner.WriteScripts(List1 scriptEntries, TextWriter outputWriter, Boolean enableCdn) +125
AjaxControlToolkit.ToolkitScriptManagerCombiner.GetCombinedRegisteredScriptContent(Boolean enableCdn) +223
AjaxControlToolkit.ToolkitScriptManagerCombiner.GetCombinedScriptContentHash(HttpContextBase context, String[] bundles, Boolean enableCdn) +18
AjaxControlToolkit.ToolkitScriptManager.LoadScriptReferences(HttpContextBase context, String[] bundles, Boolean forCombineAndMinify) +96
AjaxControlToolkit.ToolkitScriptManager.OnLoad(EventArgs e) +215
System.Web.UI.Control.LoadRecursive() +54
System.Web.UI.Control.LoadRecursive() +145
System.Web.UI.Control.LoadRecursive() +145
System.Web.UI.Control.LoadRecursive() +145
System.Web.UI.Control.LoadRecursive() +145
System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +772
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