I found myself with a black screen with a blinking cursor in the upper left corner in my Ubuntu 13.10 yesterday. I know what caused it. There was a distribution upgrade or something similar and I clicked something about configuration for my video drivers. After a reboot I was just getting the “You are running in low graphics mode”. I think I wasted 2 hours on this.
First I want to tell everyone what worked for me. Well, I would tell everyone if I remembered my exact steps. There were lots and lots of answers on the Internet but they didn’t work for me – sans the last hit I got. I had to uninstall the Nvidia video drivers ( sudo apt-get remove --purge nvidia*). Deleted the config files in /etc/X11/ and then created a new xorg file with this command: sudo X -configure. I rebooted and then it worked.
I tried switching from LightDM to GDM, I tried different Nvidia drivers. I used the recovery in GRUB. Actually, I tried just about every option in Grub. I tried lots of stuff. I also had some trouble getting into terminal to run these commands. I was clicking through the low graphics mode window and then nothing would work! I didn’t know I was suppose to hit Ctrl-Alt-F1 right at that screen to get the login screen.
I’m glad I got it up and running again but that was a 2 hr time frame on a Sunday that I would have preferred to have done something else.
Lastly, things like this can’t be fixed by a normal computer user. This was a rock-steady Ubuntu install and I got this awful issue with an automatic update. The flashing cursor would freak a normal user out. Plus, do you really want an average user using the command line? I don’t. Unless the computer user has a person like me on call or has an IT department to fix things like this I would be worried about selling a Linux computer without a support contract for the user.