it's an inherent bug in Mach3's pulsing engine.
It is definitely not a bug in the pulsing engine as you say
It will do the same thing whether you use the parallel port or SmoothStepper.
The Smoothstepper does not use the Mach Driver (Pulsing Engine)
It could however be what you say here
It seems to be related to the use of math, subroutines, or citing # variables
Best bet would be to email Andrew with code, xml and details of exactly what happens and where. If Andrew can get it doing the same then likely Brian will find the problem.
http://www.machsupport.com/forum/index.php?action=profile;u=26658Hood