The problem which I met yesterday :
1. trying to install ubuntu 12.04, and black screen (solution in the POST precedent)
2. after installation ubuntu 12.04 successfully, when reboot and black screen
There are some diagrams which could be more clear :
When you arrive at this step below, just press shift key on your keyboard.
Press e to edit your start command, change quiet splash to nomodeset and press Ctrl+X on keyboard.
After you reboot successfully, open a terminal, and follow the tips below:
You should add this option to /etc/default/grub, firstly:
sudo nano /etc/default/gruband then add nomodeset to GRUB_CMDLINE_LINUX_DEFAULT:
GRUB_DEFAULT=0 GRUB_HIDDEN_TIMEOUT=0 GRUB_HIDDEN_TIMEOUT_QUIET=true GRUB_TIMEOUT=5 GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian` GRUB_CMDLINE_LINUX_DEFAULT="quiet splash nomodeset" GRUB_CMDLINE_LINUX=""And then simply run:
You can also find the solution in the following URL, especially the answer of Coldfish in the second URL which provide a solution to update grub :