[Zope] offtopic: xemacs and zope.

Hi there folks, for those of you using xemacs and zope, what's the magic needed? I've downloaded xemacs 21.1, and the latest huge tarball of packages. When I try to login to the management screen, I'm asked for username and password, then it bombs with 'symbol's value is null: base64-encode-string' or some such. It looks like something's not installed properly, but what? not an emacs user, Anthony.