Make sure that you are using the Telerik's built in LinkManager and not the default MOSS Default LinkManager. The Default MOSS LinkManager does not work in non-IE browsers.
In order to enable the Telerik's Link manager, add the following line in the ToolsFilel.xml located in the Program Files\Common Files\Microsoft Shared\web server extensions\wpresources\RadEditorSharePoint\22.214.171.124__1f131a624888eeed\Resources folder.
|<tool name="LinkManager" />
I hope this helps
the Telerik team
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