X and y moving during operation

Okay guys I thought I posted this last night but it didn’t go in so here we have it. I was cutting a part on the mr1 when my x and y moved. Okay let me explain in the middle of the cut it made it odd sound like it was going to stall out then it restarted in a new position has anybody else experienced this. And totally messed up a $200 billet block. just to check if my x0 & y0 was in the right place and it had moved to a new location. The only thing I could think of is I have the early low-powered drivers and this may be the problem if anyone else has experienced this let me know how you fixed it