Mysterious Shift

VERY STRANGE!

I was cutting a Meshcam file, trying to figure out what has been causing severe and annoying racking on one of the axes of my machine, and 3/4 the way through the cut the X coordinate shifts from one side of the table to the other side. No drift, no power outage, nothing noticeable that would cause something like that. I figured I must have been seeing things or working too hard, so I stopped the program rewound the gcode and sure enough, the machine began with a different X origin. I must have bugs in my machine!