When Apple made the leap to the first version of Mac OS X in 2001, one advance in the new operating system was protected memory. This was huge: a crashing app would no longer take down the entire system, making system "freezes" much rarer than in earlier Mac OS versions. However, applications can still hang if they're using too much memory or having other problems. Also, the operating system can still freeze if there's a hardware problem such as a bad RAM module or a system software incompatibility.
Press "Command-Tab" to see if you can switch from the current application when an application freezes. If you can switch to another app or the Finder, the problem is application specific. Force quit that app by choosing "Force Quit" from the Apple menu or pressing "Command-Option-Escape," choosing the application that isn't responding and clicking "Force Quit."
Shut down the Mac if the problem is more serious than one frozen application by pressing the "Power" button on the computer for 5 to10 seconds until the screen and status light turn off.
Start the Mac using Safe Boot by holding down the "Shift" key immediately after pressing the "Power" button. Release the Shift key when you see the gray Apple logo appear on screen. Safe Boot performs a directory check of your startup disk and only enables extensions and systems necessary for the operation of the Mac.
Restart your Mac normally following a successful Safe Boot by choosing "Restart" from the Apple menu.
- When you force quit an application or restart your Mac using the power button, any unsaved work in open applications is lost. For that reason, you should save your work often if you've been having freezing issues.
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