Looking at the card USB port to the left for reference.
I have a sketch running. Pin 0, 1, 2, 3, 4 are used. 0 being the top RIGHT pin and then counting up going to the left.
I modify the sketch and try to upload. It won't. I have to disconnect the power to the external circuit before I can update the Arduino.
So if I move the outputs to 3, 4, 5, 6, 7 I can update the Arduino ok.
So I would seem that 0 and 1 are special for something. Is this true?