With a Debian Etch installation I encounterd the following problem:

the system was installed with an (optional) Intel Etherexpress (eepro100) as eth0. After installation the card was removed. There were still two Intel Pro/1000 cards present (eth1 and eth2).

Problem:
After reboot, eth0 wouldn't work as the system expects the eepro100 card still present.

Solution:

• Goto /etc/udev/rules.d
• edit z25_persistent-net.rules
• remove or comment out the entry regarding eepro100
• rename …NAME=“eth1” to …NAME=“eth0” and …NAME=“eth2” to …NAME=“eth1”
• reboot