Help....strange problem after calibration homing

Hi, sorry for my bad englisch. My Delta printer, prints oke, homes oke as well. But after automatic calibration and finishing 99 Itterations, My Y and Z carriages whent nice up for homing, but my X went directly down and wont stop.
Have already did a reset and other newer Marlin sketch. Even starting with emptying my Eprom (M502) and put on a new stepper driver and try calibration in Repetier and even in Simplyfy3D. Still the same issue. my knowledge stops here..any Idea?