COM Port 3 Not Found?

Hello! I've been struggling to find an answer to this seemingly simple problem: My computer won't recognize COM Port 3. It recognizes my Uno as a device on COM3, but the IDE seems to not recognize it. I noticed the TX/RX lights aren't lightning, but this may just be because it's not receiving a signal... The board was working perfectly fine earlier today, but this problem began an hour ago. I've tried rebooting my computer, unplugging and replugging the cable, resetting the board, and updating the drivers; nothing works! If anyone can offer possibilities for why I'm getting this error, I'd be very thankful!! Thanks, Jared,73748.0.html ...pass or fail?

What O/S are you using ? This is with ref to windozeXP What do you see in your Control Panel's -> System -> Device manager view of the com ports ?