I don't have any Fedora Core 4 expirence but most of the time, a incorrectly written iso is to blame. You sure its totaly frozen? You can check by hitting the caps lock or num lock and see if the light on the keyboard flickers. If so it may be in a display setting your system can't show. If you are not in need of 4 try this distro based on Fedora Core 3
http://www.blagblagblag.org/ It's super easy to install and it sets up Grub all for your config.