Arduino Leonardo not Recognised on USB

Hi All,

I have been happily using an Arduino Leonardo on a mac for a couple of weeks absolutely fine.

Today I got an Adafruit Flora and installed the Adafruit version of the Arduino IDE. Unfortunately the flora does not appear to be working as I don't get a USB option under Tools>Serial Port

So I put that to one side and go back to playing with the Leonardo but now that wont display a USB option and strangely both the RX and TX leds on the board are constantly on.

I have tried restarting the Mac, opening and closing the IDE and having the board plugged in before loading the IDE.

Does anyone have any idea or have I broken it?

Thanks in advance!