Comment # 8 on bug 1000625 from Luigi Baldoni

(In reply to Stefan Dirsch from comment #7)
> Then this sounds like the issue is being triggered by the displaymanager or
> Xsession (if autologin has been enabled and already starts when X starts). I
> suggest to switch to lightdm and chose another Xsession than GNOME/KDE?
> 
> See /etc/sysconfig/displaymanager. Displaymanager needs to be restarted.

LightDM start correctly, but then this happens:

plasma5 and KDE plasma workspace:

"Plasma failed to start
Plasma is unable to start as it could not correctly
use OpenGL 2.
Please check that your graphic drivers are set up
correctly."

Gnome:

"Oh no! Something has gone wrong.
A problem has occurred and the system can't recover
Please log out and try again."

IceWM:

No problem detected.