After switching from the proprietary to the open source AMD GPU driver via the "additional drivers" menu, my display was not recognised properly after rebooting. It was automatically set to 93Hz (60Hz display), making it respond badly. I was able to open the drivers menu again, but all options, even the proprietary driver, were greyed out, except for the selected point: "continue to use manually installed driver".
I followed these instructions to reinstall the standard driver: https://askubuntu.com/a/648920/351726
Apparently it worked, as the display is resonsive again and shows my background. However, when I boot the computer, I now get a log in screen with my username and a password prompt (I selected to auto-login at the installation). When I enter my password though, the input field disapperars for a second, the screen fades to black and the login prompt just reappears.
The password has been entered correctly, but I can not access my account, starting the guest account works. I have not changed any account settings, merely the GPU drivers, how is this possible and what can I do to get back into my user account?
The system is Ubuntu Studio 15.10.
