I never actually ran a cut with it. I only needed to have the motor drivers energized. I did manually move the head several times. It mostly crashed while it was just sitting there idle with Mach3 on the screen. It is possible the PC is messed up, and is sensitive to noise on the parallel port. I have Mach3 now on another machine (older & slower) that seems to be doing fine (except in the presence of a USB wireless module).