IDE will not upload to UNO R3 on COM

I have two Arduino UNO R3s. I attempted to upload a new sketch to one, but when I plug it in the IDE does not recognize the COM port or the UNO. I plugged in my other UNO, to the exact same port on the same cable, and the IDE sees it and uploads to it fine. I get the device detected sound from windows for both boards and they both show up in device manager. I switched out the Atmegas between the two boards, and both chips receive sketches and work fine in my second board. I can also install a sketch to the Atmega, transfer it to the broken board, and then run it on that board. (just a simple blink LED pin 13 script.)

Have I fried my board, or is there something I am missing with it?

I am running Windows 7 Enterprise 32 bit and Arduino IDE V1.0.5-r2. Note: it gives my serial port COM4 not found on the broken board, even though I just used that for the working board.

Is the "On" Led on? Did you try uninstalling your board from the device manager and install it again ?

The on LED is on. Well I just tried uninstalling and reinstalling it on Device manager and it recognizes it now!

Thanks so much zaxarias!