Please upgrade to the latest version of the RadEditor for MOSS, which now is 5.3.2. You can find information on upgrading to a newer version of RadEditor for MOSS in the following help article http://www.telerik.com/help/aspnet-ajax/upgrade_to_a_newer_version_of_radeditor_for_moss.html
If after upgrading the problem still occurs, we will be glad to help you further. In this case please provide us with some additional information. The text (HTML code) of the mentioned above list-items will be very helpful.
the Telerik team