Still I can guess that there is an MAC-filtration operation in progress on your LAN. You have not provided us with sufficient details. However if your LAN connection is configured to be PPPoE (Point to point protocol over Ethernet), then it does asks for username or password.
Broadcom Netxtreme Gigabit Ethernet Version 66400Zip password#
Because when you are on simple Ethernet, you do not need a username or password to connect. I guess you are on some sort of Campus LAN or trying to connect to the internet through some DSL service. There is nothing wrong with the Braodcom LAN Card at all, if you argue that it dials a PPPoE Connection correctly and asks for a username and password. Your problem is not at all difficult, but rather a really fundamental one. Broadcom Netxtreme gigabit Ethernet Problem.