Hi Terry, It did, but never at first, all of this started last week. I was having problems with the SS losing data, but sometimes when I used the ATZ feature I would have a problem where the X,Y origin changed. The DROs never changed, but when you pushed GO TO ZERO it was not the original 0,0. I assume this was related to the SS so I got a parallel port board. I ran a few parts and experienced the same problem, but never at the same part of the program and never while the toolpath was running. It got to the point where it was impossible to finish a part. Hood suggested to remove Mach and install a fresh copy, I did this and the machine ran great, for two parts. Then on a new part (different programming) I noticed that the 1/2 end mill was noisy and not cutting a nice clean profile. I went over to the machine and saw the tool stop in the x axis, I looked up at the screen and saw the DROs change and then the tool went in the opposite direction. I stopped the program and pushed GO TO ZERO, not the original zero. This happened on the 4th pass of a pocketing operation. The picture is posted in another post. So I ran a new part and everything was going fine and I changed out the tool, used the ATZ and when I pushed CYCLE START I saw the DROs change and the tool's position did not match the DROs readout (pic is also in another post). None of this happens at the same time, the only thing is that about 80-90% of the time it occurs after a toolchange and ATZ. BUT this is the same ATZ macro that I have been using for 4 months. Weird that all of a sudden these things are popping up, that's why I decided to try a new PC to see if that could be the problem. Ron