It was the Y axis before that was off in tolerance. BUT both axis 0,0 would appear to be reset.
The DRO does not change, what changes is 0,0. That is the only answer (or so I think), how can the machine be off when you Go To Zero? Something is changing 0,0. The DROs are really only showing a "location", they do not show true distance. The DROs have no way of knowing where they are in relation to 0,0. If they did the machine would not run off. If 0,0 didn't change Mach wouldn't be trying to move to the "wrong" place.
I think from what I am hearing that this is the same or similiar problem that Terry had with a plasma cutter.