So i seem to be having the same issue of the Self Assigned IP problem like many others here.
System - MAC G5 Quad 2.5, 10 gigs of ram - 10.5.8
I did remove 2 sticks of ram that were failing the diagnostics on boot up, while it seemed to help the system run better, nothing for the networking.
Everything else is working great - fans are normal, boots fine, no error lights, al the dust is out
I do not have a Airport Card - only connecting via ethernet to a ZOOM wireless router set-up in Ethernet Client Mode so that i can connect to the wireless service.
The wireless internet that i connect to is working fine - my thinkpad conncts just fine -it how i am loged on here now.
The ZOOM Router is connecting fine ot he wirless network too - 90-100% signal.
I have followed as many of the remides that are listed here - with about 5% success.
Deleting the Firewall Plist
Changed the Firewall PLIST to the one i found here that was modified - nada
Deleting the com.apple.network.ID.Plist / NetworkInterfaces.Plist / preferences.Plist ( I have looked at these Plists and see that they show the Correct IP to get out to the internet as provided by the wireless service 10.100.xxx.xx - but the G5 still shows the Self Assigned one in Sys Prefs/Network).
New PRAm Battery
Loaded 10.5 Server to see if they put a better set of network "Stuff" in that - Nope
Re-Installed a fresh 10.5 to no avail
Updated to 10.5.8 - still nothing.
It seems to be stuck in the Self Assigned IP "loop" if thats possable.
Its not the Nic's as i can plug the cat5 into the LAN port of the router and i get a good 192.168.x.x ip & 255.255.255.0 subnet right away
When i plug it back into the WAN Port to use the Client Mode - it goes back to Self Assigned 169.x.x.x with a 255.255.0.0 subnet
When it has worked right - it last for about 4 to 5 hours and then gets kicked to self assigned ip.
This is driving me nuts - Any info would be helpfull - Thanks.
Geting ready to load Fedora 17 on next to see if they have there act together better than Apple does.
I did see a command to bring down the Ethernet ports and then bring them up again - but i cant find it now - if anyone has that command to use in terminal i will give that a try next.