Fedora Networking :: FC10 - Unusual System-config - Unable To Ping Other Computers Or Routers

I recently built my second general-purpose server, and recently installed fedora core 10 on it. The first thing I attempted to set up after installation was the network - and that's where it's gone wrong When editing a network device using the graphical system-config-network utility, I find that the subnet mask is being automatically changed to match the default gateway address every time I attempt to modify any of its settings (or sometimes even when I cancel the changes). This also means that I cannot set the subnet mask, as it simply won't accept my setting for it. I seem to be able to get around this glitch by setting the subnet mask using the shell version of the same utility, but that doesn't solve my network issue.

Even when I use the shell utility to fix the subnet mask, I'm unable to ping other computers or routers on the network even when ifconfig indicates that the desired ip address has been taken, and other computers on the network are also unable to see the server. I'm using a wired connection and a static IP address on a network with no DHCP.