Thank you for using our online answers forum. I am sorry to hear your having issues getting connected to your Pro-HD on your new Mac book. At this point I would probably suggest a factory reset on the Slingbox , and after you have reset the box go ahead and try to reconfigure the Slingbox on setup.Slingbox.com.
Hope this helps, feel free to reply back with any other issues you might have!
The Sling Moderation Team