Also, another fix I came across. To fix multiple instances of COM port numbers for a single Arduino board on Win7:http://social.technet.microsoft.com/Forums/en/w7itprogeneral/thread/6c4a6394-0b01-4ccb-af9b-da172f554796
1. Modify environment variable to permanently the normally hidden display ‘Phantom‘ devices in Device Manager. Under Start, right-click Computer > Properties > Advanced System Settings > Advanced Tab > Environment Variables at the bottom. Click New and put devmgr_show_nonpresent_devices in the Variable Name and put 1 in the Variable Value and OK your way out.
2. Under Start, right click Computer > Properties > Device Manager. Toggle Show Hidden Devices on under view menu. You should now see the hidden installed devices all listed even if they are not plugged in.
Process is similar under XP, set environment variable to 1 and make sure view is toggled on in Device Manager. http://support.microsoft.com/kb/315539
If your computer doesn't recognize your Arduino and won't install the proper drivers, this fix may work. It has been used for Arduino UNO with Windows 7 64-bit, so steps may vary for other devices and operating systems.
1) Go to the "Unknown device" which is the Arduino.
2) Click around in the "Hardware" tab to open a window with the "Update Driver" button on it. Click it.
3) Choose the option to find the driver from a list on your computer. Then choose "Let me pick from a list of device drivers on my computer".
4) Scroll down and choose "Ports".
5) Choose "Arduino LLC" and then "Arduino UNO". If there is no "Arduino LLC" option, follow the steps below:
a) Click the "Have Disk" button.
b) Point to the Arduino folder, then to the "drivers" folder, then select the .inf file for your particular device (In my case it was Arduino UNO.inf).
6) Install the driver. Ignore any warning messages about verification of publication.
7) The Arduino should now be listed as a COM port instead of an unknown device. In the IDE click Tools > Serial Port and select the new COM port.
Full credit for the solution to this problem:
Tutorial with pictures
Tip for those without the LLC option