[Zope] Session and IE problem

[Panna Cotta]

I've build a site that uses sessions.
The setting is:
1) a web redirection to our ip: www.asite.com -> 123.45.67.89:8080
2) apache redirects with mod_rewrite to Zope
3) Zope is called with 123.45.67.89:8080/Store and sends 123.45.67.89:80 
back
4) the user has to log in and the session is created

Except of IE (I test it with version 6) all the browsers are working fine.
When I call 123.45.67.89:8080 directly also IE is working..

What can I do?
I've just searched for hours the archive...