Locate the following line in RadEditor.aspx :
<rade:radeditor id="editor" Runat"server" Skin="Skin" ToolsWidth="100%"></rade:radeditor>
Modify the following line with :
<rade:radeditor id="editor" Runat"server" Skin="Skin" ToolsWidth="100%" AllowScripts="true"></rade:radeditor>