Wawa:
I suppose you connected the 5volt supply to the 5volt pin.
Not to the V-in pin or the DC socket.It might be 'safer' to use a 5volt cellphone charger connected to the USB socket.
Leo..
Yes, the power supply has a barrel connector which I plugged in to the barrel socket on the Arduino. I have the 5v socket or pin on the Arduino tied to the +V on the bread board.