Okay:
I connect to the internet via a cable modem.
When I connect in Mac OS 9, I have to configure nothing but TCP/IP.
I set it to DHCP.
I installed Mac OS X (v. 10.0.0.4) recently.
It worked fine, too... I set TCP/IP to DHCP and I was able to connect.
Now I updated to 10.1 and I can't...