I have been noticing this pop up alot on clients machines and I have experienced it several times.  Cut a part everything is fine.   Went to close Mach3, got an Artcode Error pop up.  Clicked no on try to recover.  Open Mach3 right back up and I have to accent the agreement.  Comes up with the stock screenset and all XML settings are ZEROS
The machine is a windows 10 no internet, UC300ETH plug in.
I keep a backup of the mach3 folder, when this happens I just copy the backup Mch3 folder to the C drive.