QUOTE (Lkr @ Jul 26 2007, 01:14 AM)

its not a PCI card though. its integrated lan on my i945 mobo. Comes up in windows as intel pro/1000 lan
Ahhh. I had that same problem before and I'm not sure what I did that fixed it.
I had an internal that showed up as en0 and one day something happened it showed as a PCI card and en1. Of course this screwed up iTunes authorizations since they are tied into MAC addresses on en0. I ended up adding a PCI ethernet card and stopped using that.
Eventually it returned to normal, but I'm not sure if it was on a re-install some time later.
I would suggest removing all the network interfaces in the network system preferences. Close that and then backup then remove /Library/Preferences/com.apple.networkConfig.plist and /Library/Preferences/SystemConfiguration/NetworkInterfaces.plist
Make sure the kext needed for your ethernet is installed and then reboot. Open network system preferences and see if it re-detects the builtin and makes it en0