4walters I believe thats what network manager also resets, theres been a couple of people on irc with the problem.
rc-update del networkmanager
emerge -C knetworkmanager
That should do it, then just edit your /etc/conf.d/net and add your static ip (comment out any irrelevant lines) and then start net.eth0 /etc/init.d/net.eth0 restart
one you have your ip set in the net file theres really no need for any sort of network manager anyway, unless you use wireless.