I installed Knoppix 3.7 to my hard drive. All was well, but then I decided to use apt-get to upgrade stuff. Now my eth0 lights up, but is not recognized as a device. There is no entry in /dev for eth0 (I assume there should be). Trying to give eth0 an address, or bring it up using ifconfig yields:

SIOCSIFADDR: No such device
eth0: Error while getting interface flags: No such device

Doing ifconfig only shows the loopback. My /etc/network/interfaces reads as
follows:

auto lo
iface lo inet loopback

The /var/log/messages file has nothing of interest.

During boot, there is something about eth0 being redirected to /dev/null, but I'm not sure why. During the upgrade process it did ask to shut down the PCMCIA service and didn't bring it back up afterwards. The NIC lit up after reboot, so I thought it was fine, but then found otherwise.

I could just nuke it all and start over, but where's the fun in that? Where can I troubleshoot to find out the cause of why this isn't working. I'm somewhat new to linux, but not a complete newbie.

Hardware:
HP Omnibook 4100 laptop
3Com card-style network adapter
6gig hard drive