Last week we released a new version of the RadEditor for MOSS, which is 5.5.1. So what I suggest you is upgrading to it.
In order to get it, you should go to the Downloads section under the account attached to the license, click on the Visual Studio Extensions, DLLs, Scripts, Source Code, DNN and MOSS wrappers ... link and download the RadEditor for MOSS: (zip, 13 MB) installation. You can see the attached screenshot for more information.
You can find upgrade instructions in the following help articles.
Upgrade Instructions from version 4.x to version 5.x
or Upgrading to a newer version of RadEditor for MOSS
, if you are upgrading form version 5.x to 5.y.
I hope this helps.
the Telerik team