Even being a Mac fan as I am, sometimes you do have a problem. With a Mac very seldom but nonetheless.
The first stop in every case is MacJunky.
Kia knows his stuff, is always friendly, available at odd times and mostly able to fix the problem in a flash.Whether an install disc is stuck or looping or a crashed hard drive. It's up and running usually within a few hours (sometimes minutes).
So if you have a Mac issue, don't hesitate, to let Kia investigate. Highly recommended! Thanx man!