[CentOS] Gnome boot problem (again :-) )

Sat Nov 25 01:09:05 UTC 2017
vychytraly . <vychytraly at gmail.com>

Hello friends

I was using EL7 on gnome 3 for few months without any problem. Even 2 hours
ago I had the computer (Laptop running on Nvidia-Prime) turned on and
everything was working without flaw. But when I turned on the computer few
minutes ago, I got login screen (which does not usually happen, since I
have autologin turned on) and when I entered my login credentials I got
black screen and went back to login screen. Everytime I entered my
credentials the same thing happened so I was stuck in endless login loop.
At first I thought it was caused by gnome-extension I updated to new
version today.

So I restarted the pc, went to runlevel 3, renamed the folder with
extension in
/home/user/.local/share/gnome-shell/extensions/"extension_name" to another
name as a quick and dirty way to disable it. I restarted the pc and now I
can't even get to login screen. I get stuck at text saying: "A start job is
running for Wait for Plymouth Boot Screen to quit (25s / no limit)".

I can go to another cmdline session and when I try to run exec
gnome-session nothing happens, I just get logged off the cmdline session
and must log in again.

When I try to run startx my screen blinks and I get this output:
xauth: file /home/user/serverauth.2372 does not exist.

Output from command systemctl status gdm says:
Starting gnome display manager
Started gnome display manager
GLib-GObject: g_object_set_valist: object class "GdmSession" has no
property named "display-is-initial", GdmDisplay: display lasted 2.909...
gdm_display_finish: assertion 'GDM_IS_DISPLAY (self)' failed

journalctl -r gives me these errors:
vgargb: this pci device is not a vga device
gdm_display_finish: assertion 'GDM_IS_Display (self)' failed
Process 1165 (gnome-shell) of user 42 killed by SIGSEGV - dumping core
Process 1194 (gnome-shell) of user 42 killed by SIGSEGV - ignoring
(repeated crash)
Unrecoverable failure in component org.gnome.Shell.desktop

Please could you help me with finding the problem? I am not really sure
what could be the issue, since I did not change or update any packages
today, nor changed the configuration files. Only change I am aware of was
the update of the gnome-extension.

Thank you very much and have a nice day