Hello Juan Carlos Juarez,
I installed the SP1 on our test server, but I was not able to reproduce the issue. In order to help you further I will need some additional information:
1. Send the web.config file of your SP2010 site.
2. Send me the part of the master page where you use RadScriptManager (or the whole aspx source).
3. Send me the code where you are using RadEditor and RadAjaxPanel.
4. Send me the html code of the page where the problem occurs.
the Telerik team
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