You may see the following error in Fedora 8 while starting / restarting the network (service network restart):

FATAL: Module off not found.

Let's see how we can fix this.

This happens because you have entered a line in /etc/modprobe.conf to disable ipv6:

alias ipv6 off

In Fedora 8 you should change it to:

options ipv6 off

Now restart network:

service network restart

You will not see the error.