Is this a fresh Fedora 10 installation?
Fresh Fedora 10 installation suffer from a few problem, including yum and the GUI network setting tool, among others. Make sure NOT to use GUI network tool until it is updated, otherwise you screw the working networking setup created during installation. To update the system with yum, you need to download an updated yum RPM package and install/update it by hand. Afterwards launch 'yum update' to bring your system up-to-date.