does all of your configuration get lost or only the networking?
do you manage to at least temporarily get connected to the internet (can you ping
www.cnet.com for example)?
you could also manually configure your connection by editing the files using your favorite text editor as root:
/etc/resolv.conf (dns settings)
/etc/sysconfig/network-scripts/ifcfg-eth0 (ip settings for first lan card)
/etc/sysconfig/network-scripts/ifcfg-eth1 (ip settings for second lan card)
a possible ifcfg-eth0 for someone using mandrake who has one lan card connected to the internet via cable modem with dhcp would look sorta like this:
DEVICE=eth0
BOOTPROTO=dhcp
NETMASK=255.255.255.0
ONBOOT=yes
MII_NOT_SUPPORTED=yes
NEEDHOSTNAME=yes
the resolv.conf file would be filled in by the dhcp client when it receives the configuration from the dhcp server...