For everyone stuck at ACPI-PPC probe failed and cant even get past that, I have another solution. This is often a result after installing the 340 drivers. To fix that do the following:
Grab a ubuntu live cd and boot from it as *try ubuntu*
then open the terminal inside it and make yourself root with:
sudo -i
then make sure you mount your disk with ubuntu or the drivers installed on.
to find that out what your partition is type:
sudo fdisk -l
then once you got the partition type in the following
sudo mount /dev/xxx /mnt
where xxx is comes the partition like for example sda1
or sdb2
or sdb1
or sdb2
in my case it was:
sudo mount /dev/sdb1 /mnt
but most likely it will be
sda1
since allot of people have only one hard disk
then type in:
sudo chroot /mnt
once thats done you have full access to modify your disk using the terminal.
beware that you can leave out sudo
if you typed in sudo -i
on the beginning
now type in this command:
dpkg -l | grep -i nvidia
if you have found your driver version/name you can remove with:
sudo apt-get remove --purge nvidia-XXX
where xxx is comes your driver version. For example if we want to remove the 340.52 driver :
sudo apt-get remove --purge nvidia-340
to remove EVERY package with Nvidia written on it, use:
sudo apt-get remove --purge nvidia-*
now you can reboot again and enjoy ubuntu with sadly no good gpu drivers tough :/