I recently upgraded from Xubuntu 13.10 to Xubuntu 14.04, since the upgrade banner had been splashing over my screen at boot.
However, since the upgrade, the machine has been a little bit unstable with regards to the graphics (wouldn't suspend on lid-close, or wouldn't resume properly). I opted to select the recommended Nvidia driver. Since this point, I am no longer able to get a login screen. It boots to a black screen, and goes no further. I can see all the kernel messages and nothing seems to look too crazy, there's no stack traces or anything dumped (that I can see) at boot. If I use alt+ctrl+F1 (holding the Fn button to get F1 and not screen brightness), I can get a console login.
If there is a console way to fall back to the old open source driver that would be great. People have suggested that installing the Nvidia driver from their site works, and if I can get some kind of graphics running again, I'll be able to experiment. Unfortunately I'm currently in a public library with no install DVDs The open source drivers are good enough for now, I'm just programming.
Thanks in advance.
So I got home and just completely reinstalled Xubuntu 14.04 from scratch. It runs a lot nicer. Instead of selecting the Nvidia driver from inside the Additional Devices dialogue, I used the driver from the Nvidia website. It warned me it would disable the Nouveau driver with a file inserted within /etc/modprobe.d/. After reboot the machine ended up in a state as above, black screen after boot. No luck. It was easy to go into /etc/modprobe.d/ and remove the offending file, named something like "nvidia-installer-disable-nouveau.conf". Reboot again and it worked.
I would however, like to run the proprietary driver such that the display buttons work and the machine suspends/resumes correctly. Using the Additional Devices dialogue to install drivers leaves the system in a worse state where I cannot get in to remove the files. Using the "init=/bin/sh" trick within grub, I was able to get a root shell, and also recover from this instance too. Here, the Additional Devices dialogue install of the Nvidia drivers creates "nvidia-331-updates_hybrid.conf" and "nvidia-graphics-drivers.conf" (symlink). Remove these and the graphics return to nouveau.
Looks like the nvidia driver is failing because of the Mac's EFI. Great