More weird behaviour! But, a solution too. I fired up the PC this morning and set the power options disable sleep and USB suspend. I booted up Mach3 again and the same problem as yesterday. X axis would not move using the keyboard shortcut or the MPG. Z axis was fine and the Y axis appeared to be moving so quickly it was losing steps. Bah! I reinstalled the UC100 with admin privileges but no change. I reinstalled Mach3 over the old installation. Again, no change. Just as a sanity check I tried some MDI after zeroing the DRO's. I entered G0 X32 and all three DRO's went to .401. There was an audible clunk from one or more of the steppers but as far as I could tell nothing had moved. By now I was ready to order an exorcism on the machine because I had never seen this sort of behaviour before. As a final check, I swapped out the X and Y signal cables to the stepper motors and now both were working although with swapped directions. I swapped them back again and all seemed normal. I guess one of the axis cards was not seated properly or maybe the plug on the back of the machine controller was not fully connected. I am guessing it was the axis card as it is unlikely that all four conductors in the stepper motor plug were disconnected together. I am thinking I am dealing with more than one problem here since the machine worked fine for about two hours yesterday and then failed after the PC went to sleep. The Axis card thing may be coincidental so until I get a chance to try some more serious work with it I cannot be sure.
I have killed the screen saver as a precaution. I am a sort of glass half full kind of guy so I will just hope for the best.
Regards,
Preso