This is an invalid webresource WebResource.axd missing - Html.Editor

This is an invalid webresource WebResource.axd missing - Html.Editor

In my asp.net webform application I have a problem with Ajax HTML.Editor
control. On the content page, within the update panel, I have 3
HTML.Editor control. When I open the page Firebug records error on line
/ / START HTMLEditor.DesignPanel.js
Type.registerNamespace ("Sys.Extended.UI.HTMLEditor") ...
/ / END HTMLEditor.DesignPanel.js
On the local computer this error does not create problems and applications
behave normally. On a production server, this error makes real big
problems. Occasionally during postback it throws the user session. Elmah
catches error: System.Web.HttpException: This is an invalid webresource
request.
Relating to:
/WebResource.axd?d=o2UO8Ba564lfuU5QBNIFonwI6LzaKfPl-6oTFth2MMUjED9lYqkPs29E7nw_eLFNKT63yrJ1Mxs3mO62IDGiyP3q5_pCSeLWItuaj2vnFb3IX00Y6PRxv6IXZaLwDC_7xo-iCwiDbmuwpnnnYFqDVWgvuiB5iz1jPYg3RkSXF6A1&t=635125941825518770
On the local computer Elmah not catch any errors of this type.
I found a link to
http://blogs.telerik.com/blogs/07-03-27/debugging-asp-net-2-0-web-resources-decrypting-the-url-and-getting-the-resource-name.aspx
from where I downloaded WebResources.aspx page, which I copied to root of
web app, on the production server, and then should be able to decrypt the
above / WebResource.axd? D = o2UO .... in the name of the missing
resource. But trying on a variety of different ways always get: Error
decrypting data. Are you running your page on the same server and inside
the same application as the web resource URL that was generated?
Among other things, I found that there was an error with the latest
version AjaxToolkit concerning Html.Editor and proposed to version -
January 2013 release, which I took from
http://ajaxcontroltoolkit.codeplex.com/releases/view/100852 This reduced
the frequency of errors and the application runs more stable, but still
the problem is there.
The application is built on. NET 4.0 Framework. I use ToolkitScriptManager
Within the content pages I registered control
<% @ Register Assembly = "Ajaxcontroltoolkit" Namespace =
"AjaxControlToolkit.HTMLEditor" TagPrefix = "ajaxToolkit"%>
<% @ Register TagPrefix = "ajaxToolkit" Namespace = "Ajaxcontroltoolkit"
Assembly = "Ajaxcontroltoolkit"%>
and in web.config
<controls>
<add tagPrefix="ajaxToolkit" assembly="AjaxControlToolkit"
namespace="AjaxControlToolkit" />
<add assembly="AjaxControlToolkit"
namespace="AjaxControlToolkit.HTMLEditor" tagPrefix="ajaxToolkit" />
</ Controls>
I'm running out of ideas what to do in order to fix it.
Do you have any suggestions