nvidia - Ubuntu GNOME 16.04: System becomes Unrecoverable after locking the screen - Ask Ubuntu

i running ubuntu gnome 16.04 kernel version 4.7.10-040710 nvidia ge force 940mx gpu.
problem comes whenever keep laptop busy program (such machine learning model or gpu intensive deep learning model) takes between 2-24 hours train.

if try lock screen amidst code running or after code running, system enters unrecoverable state, wherein no combination of keys or actions effect black out screen. can't switch tty terminal check corresponding problem.

here link part of syslog file near such failure. don't know how understand syslog, else have copied exact part here.

any help/advice appreciated.