You can automatically restart the operating system when you experience crashes or blocks of various kinds,thanks to new features available in MAC OS X Lion.
To activate this mode:
1. Go to System Preferences
2. Select the item in the Energy Saver “Hardware”
3. From the new screen, enable the “Restart automatically if the computer crashes”
In this way, when your Mac to a crash of any kind, crashes, restarts automatically if you enabled the resume function, then also find all the apps and windows left open.
Macs very rarely freeze, but if you do encounter random freezes and crashes, it may be a good idea to test your RAM for defects with Ramber,a free application available on kellycomputing.net .