Following the steps I followed to enable console boot in Ubuntu 12.04
Step 1 First update your repository by running
sudo apt-get update
Step 2 There is some bug in old version of lightdm, so we need to upgrade the same. To do so run,
sudo apt-get install lightdm
Step 3 Now we have to modify grub config.
Step 3a Open /etc/default/grub with your faviourite editor and change
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
to
GRUB_CMDLINE_LINUX_DEFAULT="text"
Step 3b Also comment GRUB_HIDDEN_TIMEOUT=0 This line is for unhiding the GRUB menu
Step 4 Now we will upgrade GRUB configuration
sudo update-grub
Step 5 Now restart your machine. Voilla you will be in console mode
At any time you need after booting your system you want to change to gui mode the run
startx
If you want to restore Ubuntu’s GUI mode then
Open /etc/default/grub with your faviourite editor and change
GRUB_CMDLINE_LINUX_DEFAULT="text"
to
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
Update GRUB by running
sudo update-grub
That’s it
Credit : http://www.techienote.com/2012/05/how-to-disable-gui-boot-in-ubuntu-12-04.html
Disable the AppArmor
sudo /etc/init.d/apparmor stop sudo update-rc.d -f apparmor remove