I dont think its actualy crashed., i think its just lost communication with the SS for some reason or ss has stopped responding . When the system freezes I can walk to the back of the machine , unplug the USB from the SS board and then navigate thru mach, hit the estop , etc , all the onscreen buttons then work and I can access all menus.
Once it crashes it will stay frozen until I either force it to close or unplug the USB