Problems with 3 NIC cards Core2

[Craig Strom]

I am trying to install 3 NIC cards to a Fedora Core2 server. NAT and
masquerading will not be used. All 3 NIC cards will have internal ip
addresses. ETH0 points to my routers that a remote office will use to get to
our LAN. ETH1 points to and connects to a server on our LAN that I only want
this remote office to have access to. If I have ETH0 and ETH1 put in the
machine with no firewall turned on the remote office can access the server
fine (all ip addresses are internal). ETH0 and ETH1 will eventually have a
firewall turned up on port ETH0. When I add ETH2 with an internal address
(no firewall turned on) the routing to the server over ETH0 and ETH1 stops
working. I even go to the network GUI and de-activate the ETH2 card, wipe
out any associated routes to it, and even delete the driver. I then restart
the network service, still no routing over ETH0 and ETH1 to the server. As
soon as I pull out the third card and reboot the machine, everything works
fine again and the server can be accessed by ETH0 going thru ETH1. I want to
use ETH2 as the access point to the firewall server from our LAN for
maintenance. The point is to keep the remote office out of our internal LAN
so they can only access the server that I have connected to the ETH1 port on
this firewall machine. Any ideas?? This problem has me pulling my hair out.
Thanks in advance for any replies.