Unfortunately, I am not aware of this problem. Could you please test the Toolbar Mode
live example of RadEditor and try to reproduce the problem?
My recommendation is to make sure that you are using the latest version 2008.3 1314 of RadEditor for ASP.NET AJAX Q3 SP2 2008, because this could be due to a bug in a previous version.
If you still experience the problem, please open a support ticket and send a sample working example which demonstrates the issue. I will examine it, find the reason for the problem and provide a solution.
the Telerik team