What machine is this exactly.? You say 1m x 1m with drive belt but this tells us very little really.!! Give detailed info on mechanical and electrical setup.
Also please explain exactly what happened in relation to the pic. Did machine go in all directions like pic shows or is some of that from prevoius cuts.? Did material move.?

Like Neale says 6mtr/min is going a little but it is correct for this type of material and decent setup machine should easily handle that. However that doesn't mean your machine can handle that speed. So it could be that you have been losing position because pushing too hard for it's capabiltys.

When this happened did you hit the E-stop.? And when E-stop occurs does it drop power to the Drives.?
If so then it's possible one of your drives faulted but you didn't see because E-stop reset the drive when dropped power. However looking at the pic I'm not sure this was the case.!

Often these things nearly always boil down to 2 reasons. Pushing too hard or Mechanical / electrical issue.
90% of time it's mechanical with either lose coupler or binding bearings etc. Occasionally lose wires at the drives can cause loss of position.