After having so many problems with Windows 10 mining, I installed simplemining yesterday and I was instantly in love.
However the honeymoon did not last long.  The rig is not stable at all.

It goes offline and does not answer to reboot command issued from the web site.  This happens after minutes or hours.

When it crashes, the rig displays the following:
"Welcome to emergency mode! After logging in, type "journalctl -xb" to view system logs, "systemctl reboot" to reboot, "systemctl default" or D to try and to boot into default mode"

I usually hate pictures of screens but today that's what I am doing!
https://i.imgur.com/5dtoycj.jpg

And obviously I can't SSH to the rig when this happens.
Perhaps this emergency mode is triggered after an automatic reboot? 

Could this be a problem with bad HW? 
I actually don't trust my mobo after all the issues I had with Windows.
The OS runs from a SSD.

Any pointers would be greatly appreciated.