I just brought home the new Arduino UNO rev 3 from my local Radio Shack.
The installation was not easy or obvious. I am new to Windows 7, so that doesn’t help either.
I tried various forums with no answers that worked. This thread explains my problem:
Simply updating the driver with “Arduino UNO” on this Unknown Device did not work.
The device manager would continue to say no driver was found.
I the tried these 10 steps and it worked for me. Your mileage may vary.
Unknown Device Found.
Choose “…List of Drivers”.
Choose “Arduino LLC” and then “Arduino UNO”.
Yes – Continue to Install driver!
Voila! Driver Installed.
Arduino UNO is now seen as a COM port.
And now, yes, Arduino UNO shows up under Device Manager.
Then, in the Arduino IDE, be sure to choose the new COM port!