The version of RadEditor for MOSS, which you are using, is too old. What I suggest you to do is upgrade to the latest version, which now is 5.7.2. You can find the upgrade instructions in the following online help article http://www.telerik.com/help/aspnet-ajax/upgrade_to_a_newer_version_of_radeditor_for_moss.html
. You can download a free trial version from the Free Trials section of your account in www.telerik.com.
In mean time you can test the behavior of the latest RadEditor in the following online demo http://demos.telerik.com/aspnet-ajax/editor/examples/default/defaultcs.aspx
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