[Zope-CMF] Portal can't be viewed by everybody...

[josef_meile]

Everybody can access my start site but when few of them (a minority I 
would say) enter into the portal, then they get the normal error 
message that the browser shows whenever an url can't be reached. This 
start site is in the same server where the zope instalation and my 
CMF site is and it just has the links to the portal.

Somebody told me that it could be because the company where those 
users are accessing my site has a Firewall and it blocks my site. The 
same person told me that it could be solved if I installed Apache and 
get rid of the zope server.

I just would like to know if it's true. If not, I would like to know 
if there are other facts that could cause it.

My specifications are the following:
* SuSE Linux 7.2 (i386) - Kernel 2.4.4-4GB (0)
* Zope 2.3.3
* CMF 1.1

Thanks in advanced,
Josef.