Hi,
It would be helpful for us to see a System Report from your Mac with the Scarlett connected.
Because you will likely not want to post this in a public forum, please contact us via our web form here:
http://focusrite.com/answerbase/contact-0
After your initial email, you will receive an auto bounce back to your email address, please reply to this straight away with the following system report:
While the unit is connected on its own to your Mac, could you please send me a copy of your system profile by going to;
About This Mac >More Info >System Report >Please wait for 60 seconds >File >Save.
This will also create an email troubleshooting case for you.
Hope this helps.
Best regards
Simon // Focusrite Technical Support