Apple IMAC User Manual - Page 108

Troubleshooting Symptom Charts/ Networking Problem - 26 7 Replace the logic board. Networking Problem Unable to switch to the Ethernet network option in the control panel or unable to see any network devices. 1 Wrong option selected in the Control Panel. Open the Network control panel and select the Ethernet option. Are you able to select the Ethernet option? Yes: Verify that you can now see devices on the network. If the problem persists, go to the next step. No: Go to next step. 2 Reset parameter RAM. Hold down Command>Option> during startup but before "Welcome to Macintosh" appears. 3 Boot from the system CD that came with the unit. Does the system startup successfully? Yes: Reinstall system software. (You must use the system software CD that came with the unit to get the correct version of Mac OS .) If the problem persists, go to the next step. No: Go on to the next step. 4 Replace the Ethernet cable with a known-good cable.Try connecting to a different Ethernet port at the wall or external hub. Are you able to switch to Ethernet and see Ethernet devices on the network now? Yes: The original Ethernet port is bad. Contact your network administrator. No: Go to next step. 5 Are other users experiencing the same problem? Yes: There is a network-wide problem. Contact your network administrator. No: Replace the logic board.