Hi Its me again, I still get the occasional program stopping because Mach tells me a limit switch has been triggered although non of the warning on the diagnostics page show any faults. I have rechecked and earthed the machine, BOB and spindle drive board, shielded the wires, set the debounce on several occasions, changed the computer and checked the switches but I still get the machine stopping once a day. Luckily the stop is instant so no damage or cutter breakage has occurred. My questions is in the general config page there is a tick box to "use WatchDogs" if I unticked this box will it stop the limit switch signal stopping the program, or is it unwise to do so as it removes the overtravel limits and other protection systems. Or has it nothing to do with my problem. Jim