I've been running Ubuntu 12.04 since it's debut in 2012 without a single problem. Today I just ran sudo apt-key update && sudo apt-get update and then I rebooted my computer. After rebooting however, it first shows the Ubuntu bootscreen (with the Ubuntu logo and the dots below it) after which it booted to the command line. I could login and navigate around on the command line, but no GUI was loaded at all.
So I tried running sudo startx, but this gave a message saying (among others) the following:
NVIDIA: API mismatch: the NVIDIA kernel module has version 304.88, but this NVIDIA driver component has version 304.108. Please make sure that the kernel modle and all NVIDIA driver components have the same version.
I found this thread which suggested to do:
sudo service lightdm stop # to stop the xserver
sudo apt-get remove --purge nvidia* # to remove all driver elements
sudo apt-get update
sudo apt-get install nvidia-current
sudo reboot
After doing this, it now boots to the login screen where it seems that there are now two users named kramer65 on my computer. One of the two has the default (instead of my personal) background and says my password is incorrect. The other one seems to be my "real" account and when I type my password it seems to try to show the desktop. Instead however, it shows a black screen after which I think X.org crashes, because it loads the login screen again.
So I guess the Nvidia driver is still not okay, or maybe there is something wrong with the duplicate accounts (both with a username kramer65 (but I guess it's the Nvidia driver).
Does anybody know what else I can do from here? All tips are welcome!
[EDIT] The strange thing is that I can actually login using the guest account, so I don't understand whats wrong with the specific kramer65 user login.