I recently updated to Mach3 1.5 from 1.1 ,after resetting up all ? the perameters I encoutered this problem with the y axes only, every time I run a file the y axes over runs Zero by about .5 in when I do a goto Zero. The DRO for y axes says its at zero. If I drive it off with the jog it returns to Zero as it should. Any thoughts?

I am not sure which revision of Mach3 you are referring to - the latest version appears to be R3.043.066   

Tweakie.

Yep, Mach 3 R3.043.066 
sorry