[Zope] password box appearing on public document?

Hi, I've setup a document in a folder structure on my plone/zope site. Now, when I try as an anonymous user to open this document, I am getting a username/password (realm: Zope) box, however, when I press cancel I can open it, just as expected. But I wan't to get rid of this box, because it' public content. How to proceed? Thanks in advance, Jurgen ---------------------------------------------------------------------------