I have this problem on at least two separate machines, both of which currently run Ubuntu 8.10. Both machines are desktop machines connected to a LAN by a wired connection. Both networks have static IP addresses assigned to the machines, so I have changed the "Autho eth0" profiles on each to not configure from DHCP, and have provided the IP address, gateway, etc.
However, periodically (sometimes randomly, but mostly whenever I reboot) the network manager has spontaneously created a "new" connection setting for eth0 that boots from DHCP, and when I reboot (or when something causes networking to drop off and re-initialize) the machine ends up with a random address. I dutifully delete the extra entry, and the network manager immediately takes eth0 down and brings it back up, with the correct IP address.
My question is: How do I get the networking manager to cut this crap out? One of the machines is at my office, and if I'm working remotely over our VPN I have no way of (easily) figuring out what the "new" IP address is.