Are you still booting with the forcepae option? If not, you'll need to add it.
gksu gedit /etc/default/grub
Make GRUB_CMDLINE_LINUX_DEFAULT line look like: GRUB_CMDLINE_LINUX_DEFAULT="quiet splash forcepae"
Save. Quit. Run: sudo update-grub
Reboot and try the update again.
Are you still booting with the forcepae option? If not, you'll need to add it.
gksu gedit /etc/default/grub
Make GRUB_CMDLINE_ LINUX_DEFAULT line look like: LINUX_DEFAULT= "quiet splash forcepae"
GRUB_CMDLINE_
Save. Quit. Run:
sudo update-grub
Reboot and try the update again.