Loop-back Test Issues

Hi all, I'm new to the site and Arduino. I've got a new UNO as part of a starter kit and am having problems uploading. I have reached the point of trying a Loop-back test but have encountered some problems.

I have disconnected the board from the pc and made the necessary jumper connections (Rx to Tx and Reset to Grnd). Then when I reconnect the board to the pc, the pc does not enable the device and it does not appear in the list of com ports. Attempting to start the serial monitor returns the error 'Board at COM3 not available which I would expect given that the pc hasn't enabled it.

If I unplug, remove the jumpers and plug back into to pc, I get the power led and a flashing 'L' led. The Arduino also appears on COM3.

I wonder is the board faulty or is there something else I can try?

Any help would be appreciated.