[Zope] Handle "Unauthorized" error message

Hi guys. I have a part of my site which is protected by password. All works fine and this is really a simple task with Zope(v.2.5.1), but now, how to prevent the unauthorized user to read the error message: Site Error An error was encountered while publishing this resource. Unauthorized You are not authorized to access this resource. blahblah How do i replace that with something more friendly?(a redirect to an error page would be great too). Thanks Paolo Dina P.S.: i know that Cookie Crumbler makes something similar, but i won't use it in my site.