I've not found this specific problem in the Forum, and would be grateful if anybody can suggest what might be the cause and cure.

The NIC is recognised, and successfully gets its IP address from the Router, but it will not come UP and connect to the internet (nor anything else).

ifconfig (alone) just displays the local loopback, implying by omission that eth0 is DOWN.
The following typical terminal ouput (annotated) was taken with the live CD running in a COMPAQ Presario, and shows the interface status, configuration, and failure to connect with the Router (192.168.2.1) :-

root@1[root]# ifconfig -v -a
eth0 Link encap:Ethernet HWaddr 00:30:BD:07:40:F0
inet addr:192.168.2.55 Bcast:255.255.255.255 Mask:255.255.255.0
BROADCAST MULTICAST MTU:1500 Metric:1 # NOTE ! No "UP", no "RUNNING"
RX packets:10 errors:0 dropped:0 overruns:0 frame:0
TX packets:10 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:3780 (3.6 KiB) TX bytes:3372 (3.2 KiB)
Interrupt:17 Base address:0x1080

lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope: Host
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:14 errors:0 dropped:0 overruns:0 frame:0
TX packets:14 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:700 (700.0 b) TX bytes:700 (700.0 b)

sit0 Link encap:IPv6-in-IPv4
inet addr:127.0.0.1 Mask:255.0.0.0
NOARP MTU:1480 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)

root@1[root]# ifup eth0 # (Still doesn't work)
root@1[root]# ifup eth0
ifup: interface eth0 already configured
root@1[root]# ping 192.168.2.1
connect: network is unreachable
root@1[root]# pump -i eth0 -s
Device eth0
IP: 192.168.2.55
Netmask: 255.255.255.0
Broadcast: 255.255.255.255
Network: 192.168.2.0
Boot server 192.168.2.1
Next server 0.0.0.0
Gateway: 192.168.2.1
Gateways: 192.168.2.1
Boot file: ÿ
Domain: Belkin
Nameservers: 192.168.2.1
Renewal time: Thu Oct 5 05:48:23 2006
Expiration time: Thu Oct 5 07:18:23 2006
root@1[root]#

Exactly the same happens with Knoppix 5.0.1 running in my other, "white-box", machine (NIC is COMPAQ NC3120 , for which the e100 driver is installed), whether as :-
- Live CD or
- CD ISO image in VMPlayer on HD-installed Knoppix 3.7.

Remark (1): When the 5.0.1 files are extracted to HD for re-mastering and the system run in chroot, the system successfully "hitch-hikes" upon the host Knoppix 3.7 (2.4 kernel) system networking.

Remark (2): Knoppix 5.0.1 above is v.5.0.1-CD version 2006-09-01. md5sum of the KNOPPIX file is correct.

Remark (3): The Knoppix 5.0.1 DVD behaves in the same way, and so does Musix, a contemporaneous derivative. (My search for other suitable candidates continues...)

Remark (4): I do not suspect a hardware issue, as:
- It happens on different PCs,
- Mepis and Kubuntu and Suse (all 2.6 kernel) network OK on the hardware.

(Why not give up and use Mepis or Kubuntu ? They are splendid for simple desktop use, but Knoppix provides a more Debian-like basis for further personalisation ... and Knoppix 3.7, the last using the 2.4 kernel and that fully works for me, has gone about as far as I can take it with Debian Backports and compiled programs.)

Thanks to the many helpful posters on the Forum [/list][/code]