KAWASAKI MULE- REGULATOR PROBLEMS?

MY KAWASAKI MULE KAF450 twin cylinder water cooled 2WD. engine cuts out when battery is fully charged. will idle ok and will run for longer with lights on. HAS MELTED original regulator, a new genuine kawasaki regulator seems to have failed. i fitted another regulator from kawa gt550 last night and it drove great for 10 minutes test. this morning ran ok until engine warm/ battery full THEN SAME CUTTING OUT. ALSO HAD A BEEPER GOING OFF AT SAME TIME UNTIL I DISCONNECTED BEEPER MONTHS AGO. the most useful vehicle i have is mnow unusabe. PLEASE HELP