Gcode placement

I'm confused!

I am useing 8.4 (Hardy), Axis interface, on a gantry router.

I made up a jig to hold my material and have CAD work and Gcode for same.

I'm running parts one after another with great results, I get to the last part (naturaly) and load-up material and start things up.
The machine dumped the profile on the material -.300 in Y for some reason.
Shut it down, restarted and it's fine.
What would cause this to happen?

Thanks

Hi

There are all sorts of things, from missed steps, co-ordinate system change, to tool compensation having been taken off or put on when not expected.
(M2 or M30 will do both of the latter)

If the distance is absolutely consistent and exact, would suspect it is something in the settings or lack thereof.

Without a lot more info, just guessing

regards