Couldn't make an internet connection using Knoppix 5.0 until I saw Duncan Macdonald's April 3, 2006 post. Now it works great. So give it a try.

Bring up a console window and enter the following commands:

su
ifconfig eth0 up
route add default gw 192.168.2.1 (or whatever the IP address of your router is)

Hope this works for you.

Peace, Earl