Have run again this evening about 20 or so times and each time the X and Y offsets change. What version of Mach are you running?
Hood

I'm a little embarrassed.  My manual said version 1.84, but when I hovered my pointer over the Mach 3 file it said Version 1.0.0.1.  I installed Version 2.63 yesterday and will be running some dual Z files today.  I'll post the results.

On the plus side, I've been holding off upgrading due to still being a bit overwhelmed with the new system.  Not having a step by step upgrade guide had me a little apprehensive, but the upgrade process went smooth as silk.

The easiest way to see what version you are running just go to the Help menu in Mach and then the About Mach3 CNC Control, a window will pop up with the revision and whether you are licenced or a demo.

Hood

More ruined parts today.  The problem seems to come and go.

What I noticed today is that if there's going to be a problem, it happens when Mach first loads the part file and runs through the code.  Randomly it will not switch completely back to the main Z head even though there was an M101 command at the end of the file.  I've tried inserting pauses in case it's a timing issue, but no luck.

Here's a small file for verifying center.  It's working fine now, but when I first used it today, I had a Z swapping issue and crashed into the part.  Re-set everything, tried an air cut and it worked fine, mounted a part and had another crash.

M101

G0 X0Y0

M102

M8

N10 G00 X117.839 Y10.975 Z45.000
N11 X117.839 Y10.975 Z38.000
N12 X117.839 Y10.975 Z114.000

M9

M101

G0 X-700