[DanThe]

My network settings say the cable is not plugged in, ive changed the cable and tried the router on another machine.
The only way I can get it to work is by using a different hard drive, if I copy my apps and folders accross to the new hard drive the problem comes back.

Where do I look for problems?

Cheers,
Dan

[pcguy1]

There is only 2 problem/solution that I can think of.

1. Your ethernet port/chipset is dead, in which case only a repair(under warrenty), or replacement card of some kind.
2. Somehow your OS get screw up so badly that it won't turn on the ethernet port(very very unlikely), a reinstall is the only for sure method to fix that.

this is assuming that your router is working and not the problem.

[Sherman Homan]

Are saying that the ethernet port works when you boot from another drive?
Then the problem is not the ethernet port. But it can't be from copying the Applications folder either. I would stick to your original hard drive and delete all of your Network settings. Delete the com.apple.networkConfig.plist file also.

[DanThe]

I really dont want to have to reinstall everything, it would take me weeks.

Yes the port works fine when booted from another drive which to me means some settings have got messed up somewhere.
Do you mean the settings in System Preferences - Network?

Cheers

[Sherman Homan]

Yes, go into the System Preferences --> Network and delete 'em all. These are software settings, even if it does give you a scary message about not being able to undo it. Then delete the plist file just for good luck. It shouldn't be necessary, but since yours is messed up it won't hurt. Log out, log in, go back to the Network settings and see if your ethernet comes back to life.

[DanThe]

It worked!
I deleted the built in ethernet port configurations, ticked the box again and it came back to life as if nothing had happened.

Thanks