Question on BDI-4

I am running BDI 4.38 with Jon's PPMC cards and a Bostomatic mill. Today
running a Meshcam file to do some engraving in wood the EMC would just stop
like it was paused. The spindle didn't stop it just stopped progressing
through the file. I tried "resume" and nothing happened but when I tried
"step" it would proceed on and then "resume" would work. This happened many
times over several hours. Sometimes only a few (5 or less) min. between
events other times like 20 min. The machine reported NO errors when this
would happen, and the comand it had just executed and was about to execute
were normal moves line G1s. sometimes single axis other times multiple axis
(no stops or pauses)

Yesterday ran a similar (but different) file for hours with NO problems or
stops. Feed rate was higer today.

Any ideas?

Thanks, Beau