Hi board! I have a 13" MacBook Air 2011. I bought this Mac originally loaded with Lion and cleaned installed Mountain Lion the day it was released back some time in the summer. I've noticed the system occasionally freezes and the only way to get it back up and running is to hold down the power button and boot it back up. I'm currently on the latest version 10.8.2. This has happened more or less 4 times since I upgraded to Mountain Lion. I never turn off my Mac and only do when my system freezes. Is this a known bug within Mountain Lion or a potential hardware issue. Many thanks!