AT AROUND 11:35 AM, AS I WAS TURNING LEFT FROM PRAIRIE STREET INTO THE FAR SOUTH ENTRANCE OF KROGERS' SUPERMARKET. THE CADILLAC'S ENGINE JUST STOPPED RUNNING. I WAS UNABLE TO TURN THE STEERING WHEEL FAST ENOUGH TO COMPLETE THE TURN WITHOUT JUMPING THE CURB. AFTER COMPLETING THE TURN, I PLACED THE CAR INTO NEUTRAL AND HIT THE STARTER A FEW TIMES. THE ENGINE CRANKED BUT FAILED TO START THE FIRST FEW ATTEMPTS (AT LEAST I THINK). I WAS ABOUT TO START MY PROCESS OF EXITING THE CAR, WHEN I NOTICED THE TACHOMETER SHOWING 600 RPM. I WAS REALLY HESITATE TO DRIVE THE VEHICLE ANY FURTHER, SO WE PROCEEDED TO DO OUR GROCERY SHOPPING. I REMOVED THE IGNITION KEY FROM THE CAR'S ENTRY REMOTE AND MY CLUSTER OF PERSONAL KEYS. AFTER STOWING THE GROCERIES AND CHECKING MY COMPUTER FILES FOR THE PREVIOUS REPORTED CADILLAC'S PROBLEM CONCERNING ONSTAR DISABLING IT IN AUGUST 2008. I MADE SOME OPERATIONAL CHECKS OF THE IGNITION SWITCH. I REALLY HAVE MY DOUBTS THAT THE WEIGHT ON THE KEY WOULD CAUSE SUCH A MALFUNCTION, UNLESS THE IGNITION CONTROL CIRCUITRY IS GROSSLY DESIGNED. *TR