Problem- Machine will move on its own.

[Farmers Machine]

Yesterday and today about 7 or 8 times the oxy fuel gantry torch would start to move after the part was cut and M30 issued. it would not do it every time, some times with in 2 minutes up to 30 minutes after a part was cut out. a lot of one offs. it would move X or Y or both in either direction very slowly for 2 to 3 inches then alarm out saying motor was off can not move.
you could not activate the jog icon. the drives were not errored out. if you hit esc. then answered no to turn off control the machine would thump, kinda like all axis motors moved 0.05 at the same time. this machine just came through the hottest Texas summer on record with out a problem,
Tuesday and Wednesday morning it was in the high 20's and that was when the machine acted goofy.
Thank You
The Farmer

[Al_The_Man]

It sounds typical of the symptom of the motor command to the drives being shut off for some reason as in a MO command without any external disable of the drives occurring or present?
It probably errors out when the encoder count reaches the programmed error limit.
Al.