[Zope] Authentication with IE 6/7

Has anyone reported problems authenticating with Zope when using the version of Internet Explorer that comes with WinXP? One of my users (a computer literate one at that) cannot authenticate as an owner when using IE 7. I've tested the Zope site using Netscape 4.7 (in Linux/Windows), I.E. 4.x (Windows), Mozilla (0.9x in Linux), Galeon (Linux) and Konqueror (Linux). All without problems. I've recommended that she get Netscape, but I was wondering if anyone knew of something specific to tell the user to fix in order to remedy the problem. Thanks in advance, Ron