i have grounded my case, the shields on my wires. i have changed my printer cable. i have created a new profile in Mach 3. still having the original problem, the probe light flashes and the touch off doesnt work. i did run the driver test as suggested in the Mach 3 manual. when the test firsts starts it says the pulse is too fast, it comtinues and at the end it says everything is OK. i am open to suggestions. i dont think a capacitor is going to fix anything but thats all i have left. could it be a Mach 3 problem or something with the screenset? this bums me out, since i really like the screenset and the touch off portion. i use the tool change in all my g codes, makes things so easy to just change the bit and press a button. next best would be an automatic tool changer.