Comment 10 for bug 453678

It is said that this bug also is responsible also for Ubuntu not booting, giving following text in first 3 seconds after booting:

GRUB loading.
  udevadm trigger is not permitted while udev is unconfigured.
  udevadm settle is not permitted while udev is unconfigured.
  svgalib: cannot open /dev/mem

which makes computer fully un-bootable. See bug #515950 (now marked as duplicate of this one)

The work around is following (thanks to <slangasek>)
(re)Start computer
If you have grub2 installed, you need to hold down the shift key while booting. If you have grub1 installed, you need to hit escape.
Now you can select the older kernel version from the grub menu
The system will boot normally.
Now open a console and run root command:
sudo update-initramfs -u
that will regenerate the initramfs for the newest kernel,
and after reboot all will work in the newest kernel also.