[Zope] On a CMF site, when user get "404 Not Found" error, it appears they are logged out automatically....

Hi, In a CMF site, (Plone site too) when a member tries to load a page that doesn't exist. They get the site error page. However, this page gives the appearance as if the user as been automatically logged out. Because, in the header of the site, CMF displays the user as Guest, and plone displays "you are not logged in". Is this a bug, or is there a reason behind this behavior. I am using zope 2.7.4, cmf 1.4.7, plone 2.0.5 Thanks, Gary