Well my ghost is still around.
Ran a new file yesterday and had no issues. Ran the same file again today and ran into the same issue, sort of, as in my previous post.

Tool-paths were:
3D roughing cut
3D finish cut
V-carve some text
Flip the project and V-carve my logo on the bottoms

On the first logo cut the Spindle moved away from where the cut should have begun and the bit plunged almost through the wood before I could stop it.
Shut down my ‘puter and the SB control and rebooted everything and ran the file without an issue. Thankfully when the cut went wrong it had moved away from my workpiece so it didn’t ruin it.

Implementing the suggestions from my previous posting didn’t seem to help. The only thing that is common with both these issues is that it was the cut following a lengthly (five hour) finish cut.

So now when I begin a cut my hand will be hovering above the E-stop switch as there is too long of a delay when hitting the Spacebar.