I went through exactly this with a new Xtools D1 last year, spending hours trying to track down the fault, and thinking that the controller board or the power supply was faulty. Changing to a high quality USB cable fitted with ferrites at each end solved the problem. I also added a ferrite to the power supply cable where it plugs into the machine. If you have a selection of old cables lying around you may find some of them fitted with snap-on ferrites that you can rob to fit to your laser cables. But I can’t stress enough that you need a high quality cable - a name brand such as Belkin, Apple or Logitech if possible.