I suspect the problem lies with your circuit board.
However, if you post you .xml file - the one which is located in the Mach3 folder named <your profile>.xml (typically Mach3Mill.xml) we can check that you have Mach3 set-up correctly. Copy and rename the file to kminnaar.xml, use the forum 'Reply' button and select Additional Options' to post the file.
Tweakie.