Thanks Tweakie,
Further details on the problem:
I load Mach3. If either X home or Z home limit is active, the flood and mist are energized after about a 2 sec delay. They can only be turned off by moving the X or Z on to the overtravel limit. When I come off the overtravel, they come back on. when I come off either home limit they stop. If I cycle the overtravel a couple of times, the problem clears and I can run a program normally with out further problem.
If I shut down Mach3 and restart, the problem returns.
Is this possibly a known bug in Mach3?