Connected/Disconnected

A buddy of mine is running a Dell Dimension 2400, and his internet connection keeps flashing on and off (Connection:100mb/s, then 'a local area network connection is unplugged.) Needless to say (but I’ll say it anyway) he can’t get online and asked me to help out.

The only thing is, I’ve no fraggin’ clue. Under Control Panel, it lists two ethernet connections which is funny because there’s only one port. I tried disabling the secondary network connection network connection, no dice. It says that there’s a protocol that’s not supported.

I tried a different ethernet cable and a different port on my router, no dice.

Any ideas, anyone? Thanks in advance! :cross-eye