Confirmed on FC3.
Interrupt Grub and edit the boot options. Add the option
single
to the kernel line in your appropriate Grub entry. This will be the "kernel...vmlinuz...." line.
Let the system boot and you will come up with a shell prompt as user root. You can change the password for root there.
When you exit from this shell, you will reboot in the default runlevel.
Sorry for the new thread...I changed machines to test. Erik
