I try to quickly summarize the problem and what happened (details about system are below). I know there exist many similar questions however none of the answers did help in my case. I did not fiddle with any new drivers, applications, user privileges, file permissions or whatsoever. Also I did not start any graphical application via sudo or modified my .profile or .bashrc files. I did check the integrity of my .Xauthority file.
So when I (re-)start my computer it takes me to the login screen as always, however after entering my credentials (and some loading time) the screen turns black for like half a second and then I'm immediately logged off. During that very short period it also displays the following message:
/dev/sda7: clean, 659285/8429568 files, 7752992/33709961 blocks
During the last (successful) session I experienced a graphics bug, specifically when Alt+Tabbing it won't show the application tabs anymore (though the tabbing itself worked). I realized this when I wanted to tab out of Firefox (if that's important in any case). I wanted to get rid of this bug and so I restarted the computer. During that session my computer used lots of memory (more than the available 16GB) and hence was swapping out.
Error logs
I checked the ~/.xsession-errors file and it has the following content:
X Error of failed request: BadValue (integer parameter out of range for operation)
Major opcode of failed request: 154 (GLX)
Minor opcode of failed request: 3 (X_GLXCreateContext)
Value in failed request: 0x0
Serial number of failed request: 29
Current serial number in output stream: 30
upstart: gnome-session (Unity) main process (2060) terminated with status 1
upstart: unity-settings-daemon main process (2039) killed by TERM signal
upstart: logrotate main process (1859) killed by TERM signal
upstart: upstart-dbus-session-bridge main process (1932) terminated with status 1
upstart: upstart-notifier-release main process (1934) killed by TERM signal
upstart: hud main process (2037) killed by TERM signal
upstart: Disconnected from notified D-Bus bus
upstart: bamfdaemon main process (2028) killed by TERM signal
upstart: unity-panel-service main process (2077) killed by TERM signal
upstart: window-stack-bridge main process (1884) killed by KILL signal
There are lots of log files in /var/log/lightdm with lots of content but since I don't know what I should be looking for I didn't seek through all of them.
System
- Ubuntu 16.04.5 LTS
- Kernel: 4.4.0-134-generic
I run a NVIDIA graphics card which (I suppose) is used by default for graphics output (at least it was the last time I checked). Running lspci -k reveals:
00:02.0 VGA compatible controller: Intel Corporation Broadwell-U Integrated Graphics (rev 09)
[...]
Kernel driver in use: i915
Kernel modules: i915
08:00.0 3D controller: NVIDIA Corporation GK208M [GeForce 920M] (rev a1)
[...]
Kernel driver in use: nvidia
Kernel modules: nvidiafb, nouveau, nvidia_drm, nvidia
Any help is highly appreciated. Thanks.
