Hi, my printer will not connect any more! It has been working ok for about two weeks, but suddenly I get "Access to the port 'Com3' is denied". I have tried another cable, another USB port, and even another computer, but get the same messge. The device manager reports that COM3 is connected to Ardunio Mega 2560. AND, I tried to load a G-code file from an SD card, and the card reader does not eby KalleK - Prusa i3 and variants