This solution is specific to billcat's problem, i.e the driver stops working after some time of use. I too faced the same problem i.e I was able to use my arduino clone one whole day based on microchip MCP2200 . The next day , after restarting my pc it stopped working. My pc is windows 7 64 bit. Steps : 1. You may not find any com ports listed in the device manager, but if you see any specificby hussainb - Next Wave Electronics Working Group