You could also try restoring from a backup from before the problem started. All it requires is the moving and renaming of a file. Cut the existing XML file from the Mach3 folder that matches the name of your current profile, i.e. Mike's mill, and put it some place else like the desktop. The go into the XMLbackup folder and pick a file from before the problems started. Rename it the same as you old XML file, cut and paste to the Mach3 folder. Open Mach3 and you are back where it used to be. If this doesn't work, a reload of Mach as Tweakie says would be next.
I do this on my mill when Mach3 gets wonky on me. Makes all the problems go away.
This is also why I am going to Mach4 since it doesn't seam to have this silly problem.