The fan should cycle on and off as needed, usually stays off for quite a while.
The fans on both my ThinkPad and Presario stay off for a long time but never has anything locked up because of the heat.
To take software out of the equation, boot into and stay in bios, see if the same issue occurs.
The cooling fan is mimiscle to say the least so just a little dust in the air outlet will stall any airflow. Also, the foot pads under the NB might be worn or missing, that starves the fan.