Go to the Extensions manager (located in the control panels)
If the Extensions Manager crashes when you try to run it trash the extensions
manager preference folder
The path to this folder is Hard drive->System Folder->Preferences
folder->Extensions Manager Preferences
Scroll down until you see the extensions folder
Make sure there is a check box next to the ethernet driver extension
This extension has many possible names. Common names this extension might
have are:
Ethernet
Ethernet (built-in)
Apple ENet
Once the extension is checked restart and try to connect again
If you still can't connect (or can't find the ethernet extension) then it's
time to nuke and pave
