Funny that noise is mentioned, because this can be a real pain of an issue to diagnose. A few years ago I had a little refrigerator in my shop (beer!) next to the PC, with the USB cable going to one of my printers running behind it under the workbench. Kept experiencing all kinds of random disconnects with no real pattern I could see based on what was going on with the printer or computer. Took a bit, but then I realized that anytime the compressor powered on while the USB connection was active, it would halt and reset the Arduino. Re-routed the USB cable and moved the fridge, problem solved.