Dell Optiplex GX150 and Windows xp sp2. Cannot get network cable to work. No nic card lights. Have tried 3 different machines and 3 different cat5 cables. IT insists port is live, and a wired laptop does connect okay. Have tried internet search fixes including registry changes, installing netbui, etc. to no avail. Have reinstalled driver. Have also tried changing media types for nic. Help!