system-config-network problem

[Gerhard Magnus]

I'm in the process of replacing FC9 with FC10. As the boxes on my LAN are 
ethernet-wired I've disabled NetworkManager and am running network. 
Everything is working normally (access across the LAN and to the Internet) 
except on the machine on which I have just installed FC10. Something keeps 
replacing the Netmask entry I want for eth0 (255.255.255.0) with the 
Gateway address (192.168.1.11). This occurs in both the 
system-config-network widget and the 
/etc/sysconfig/network-scripts/ifcfg-eth0 file. So I can't reach the 
Internet from this box (although I can ssh to the other machines.) This 
rewriting of the Netmask field keeps occurring in both places no matter 
where (or how many times) I make the corrections. The network-scripts 
directory does not contain a route-eth0 file which, in my understanding, 
is another place where this problem might be occurring.  Thanks for the 
help!

Jerry