mercedes c203 engine 272

When I start my car doesn't start, then I make several efforts and sometimes
it starts, and after some seconds the car turns off, the display writes "coolant
stop.engine off" . But the temperature is normal, and not so hot. Sometimes,
the car starts and I drive normal, but in major times, the abovementioned
problem remains. And sometimes, when the car starts, I drive it but the
display shows the same as said above. Pls. help, what may be problem