Overheating.
As Machead said, a thermal sensor is loose or damaged, or the thermal paste seal between the heat sink and various chips (most likely the processor) has been broken.
A jolt will break the seal between the heatsink and the component it is drawing the heat away from and so will no longer function efficiently, allowing the component to overheat and shutdown to avoid any permanent damage.
The existing thermal paste will need to be removed and reapplied.