This may be completely a completely unrelated problem, but I figured I'd put it here anyway.
I updated the kernel from 2.6.9-1.667 to 2.6.10-1.770_FC3 using up2date. It told me to reboot, which I did. On restarting it gave me 1 line saying GRUB and hung.
I went into recovery mode using the Fedora CD and looked at the grub.conf file. Everything seemed to be okay, both kernel boots were there and the files were in /boot like they should be, so I thought maybe the two kernels were conflicting. I commented out the 9-1 kernel and rebooted. Same thing. Then I decommented the 9-1 and commented the 10-1, so Grub should see the file as being exactly the same as it was before. Reboot, same thing.
How could the kernel install have screwed up Grub so badly?