INJURED CLAIMS TO HAVE BEEN USING AN OVERHEAD HOIST TO RAISE A CRATE OF SCREEN PANELS UP TWO FLOORS IN THE SCREEN HOUSE. WHEN THE LOAD WAS BEING LOWERED IT BECAME CAUGHT ON A HAND RAILING. WHE N THE CRATE WAS MOVED OFF THE RAILING IT DROPPED SLIGHTLY, WHICH STARTLED THE EMPLOYEE. HE STATED THAT HE MOVED BACK AND OFF TO ONE SIDE AND HE FELT SOMETHING POP IN HIS BACK.