Machine shuts down when I use the zeroing plate

[JBell]

I’ve done it the same way countless times with no issues.
Now, when the bit lands on the zeroing plate, the spindle head growls for a moment and the machine shuts down. The monitor reads “Stopping…” then “Tool Stop Button On” when nobody touched it. I’ve rebooted everything a dozen times, cleaned all the contacts I could think of but nothing seems to work.
Any of you wonderful people out there have any ideas?
Thanks.

[JBell]

Oh, it’s a PRT96 Alpha with a Colombo spindle.