Interestingly enough it seems related to the udiskd daemon. At least this 
is what I am seeing for a second in the log upon crash before being 
presented with login screen.

Another thing I've noticed is that about the same time the crashes started 
a glitch in E19 appeared as well. Again random, when I am trying to close a 
window on the taskbar the mouse would move precisely to the center of the 
screen and does that constantly until reboot.

On Friday, September 4, 2015 at 6:50:49 PM UTC+3, Frankie Wild wrote:
>
> I believe it's since I installed latest updates two days ago. 
>
> At the time it occurs I get a black screen with a few lines of errors and 
> then back to login screen.
>
> I couldn't memorize what the errors were at the time. I have checked all 
> logs in /var/log to no avail... 
>
> Where could they be, so that I can post more info on the errors ? 
>