[Zope] cookie problem in IE

Here's another issue I've been having. In my companies intranet, there are a lot of links to other resources outside of our system. I'd like to link to these resources in a frame (<iframe> actually). That way the user is still in my system and can access other resources. However, many of the external systems require login. The problem is this: In IE and only in IE, the cookie is not sent. If I set up the same page on an apache server I can log into a system and proceed as usual. But in Zserver and IE, I can log in but I'm immediately logged out when I try to do something and I get an expired cookie error. Has anyone else experienced this? Thanks, Jacob