Double click the device you believe is the Arduino. Click “Reinstall driver”. You should end up in the Hardware Update Wizard. Select the “install from a list or specified location” radio button. Click “Next”. Now select “include this location in the search”. Click “Browse” and navigate to the /arduino-1.0.4/drivers folder in your Arduino dowload. When you click on that folder, the OK button should highlight and you should select it.