F65 Error

Please help:

Getting the following error, anyone know how to fix?

"Following Error 0 Ctlr Error 201, Auto Shutdown executed (M87, M88) Forces NAK to FLEX-CNC
Auto shutdown executed (M87,M88) Forces NAK to FLEX-CNC, Controller Error
Following Error 0 Ctlr Error 101 Auto shutdown executed (M87, M88) Forces NAK to FLEX-CNC"

it happen when I go to move to Zero or (Move to #1). The Vertical goes up like it should then on its way traveling down it stops and freezes up throwing the above code.