I have Late 2012 27" iMac, 3.4GHz, GT680MX, 32 GB RAM, so basically my machine is more than enough to edit pictures. Whenever I use brushes, the computer freezes up and have to hard boot. I have no other programs open. Running OS X 10.8.2, and A3 is 3.4.3. Anyone else experience this and how did you solve it?