Comment 24 for bug 108578

I see the exact same behaviour since upgrading to feisty, although with a slightly older card that needs the 'nvidia' module, as opposed to 'nvidia_new'.
I don't remember exactly, but I might have used the nvidia-installer somewhere in the past.

Symptoms are: first it works fine, but after a reboot, X can't start.

When I try to load the nvidia kernel module, "modprobe nvidia" says:
FATAL: Could not open '/lib/modules/2.6.20-15-386/volatile/nvidia.ko': No such file or directory

I can "repair" my ubuntu by doing a
sudo apt-get install --reinstall linux-restricted-modules-2.6.20-15-386
after that,
sudo /etc/init.d/gdm restart
successfully starts X

That package doesn't contain the missing file, but reinstalling seems to create it in a way.
Of course, it's gone when I boot the system again.

I did all the checks mentioned above in this thread and see the same things like kry10.