I want to modify the above comment, as I just had similar misbehavior from my Ubuntu install running a different app, Synaptics.
System froze after a few minutes use of Synaptics (running Ubuntu 16.04): "the only possible action is moving the mouse pointer on the screen. Impossible to connect to a tty session to kill Xorg."
Again, I did manage to reboot using FN + ALT + SYSRQ + REISUB, same as above.
I want to modify the above comment, as I just had similar misbehavior from my Ubuntu install running a different app, Synaptics.
System froze after a few minutes use of Synaptics (running Ubuntu 16.04): "the only possible action is moving the mouse pointer on the screen. Impossible to connect to a tty session to kill Xorg."
Again, I did manage to reboot using FN + ALT + SYSRQ + REISUB, same as above.