MD83 CREW HAD STICK SHAKER AND STICK PUSHER ACTIVATE AT 50 FT AGL.

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IT WAS MY FO'S LEG. HE FLEW A PERFECTLY NORMAL ILS UNTIL ABOUT 50 FT AGL; THEN DURING THE LNDG FLARE; THE STALL WARNING STICK SHAKER PUSHER ALL ACTIVATED. WE WERE FLYING THE CORRECT VREF SPD. APPARENTLY WHAT HAPPENED IS A WING LEADING EDGE SENSOR FAILED AT THE ABSOLUTE WORST TIME WHICH FAKED THE AIRPLANE INTO THINKING WE WERE IN A DEEP STALL. THE FO REACTED INSTANTANEOUSLY BY JERKING THE NOSE BACK UP AND APPLYING MAX PWR. WE STILL HIT THE RWY HARD; BUT I'M CONVINCED HIS INSTANT REACTION SAVED STRUCTURAL DAMAGE. AT ANY HIGHER ALT WE COULD HAVE GONE AROUND OR AT A LOWER ALT THE AIRPLANE WOULD HAVE LANDED HARD BEFORE AN EXCESSIVE SINK RATE DEVELOPED. THIS IS; BY FAR; THE MOST CRITICAL MALFUNCTION THAT I HAVE SEEN IN OVER 19000 HRS OF FLT TIME. I THANK GOD THIS DID NOT HAPPEN DURING A LOW VISIBILITY CAT III AUTOLAND OR ON A SHORT; WET; OR SLIPPERY RWY SUCH AS BUR OR SNA. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE CAPT RPTS THAT ALL OF THE MD80 SERIES HAVE STICK PUSHERS. THE MD80 SERIES HAVE MECHANICALLY ACTUATED ELEVATORS WITH A TAB SYS FOR ACTUATION. THE STICK PUSHER; HOWEVER; IS HYDRAULICALLY PWRED; AND TAKES A HIGH FORCE TO OVERCOME. THIS ACFT HAD A TOTAL OF 3 INCIDENTS. AFTER THE RPTED INCIDENT; MAINT REPLACED THE STALL WARNING COMPUTER. THE SAME INCIDENT OCCURRED ON THE NEXT FLT; HOWEVER; AT A MUCH HIGHER ALT. MAINT THEN ADJUSTED THE LEADING EDGE SLAT SENSORS. THIS DID NOT HELP; AS THE FALSE STALL WARNING OCCURRED AGAIN ON THE THIRD FLT. THIS TIME; MAINT REPLACED THE LEADING EDGE SLAT SENSOR SWITCHES. NO FURTHER INCIDENTS WERE RPTED.