racer2012,
I use Mach3 version 3.043.062 and XP Pro. Your file had some bad gcode and characters.
Mach highlights the bad characters or code when it loads.
Don't get hung up on the number of lines Mach will run in demo mode. It could be more or less than 50
or whatever. I have found that if you call a subroutine or sometimes a canned cycle it may be less in lathe.
RICH