How to Close Frozen Applications in OS X
If you've ever encountered an unresponsive program in Windows (and who hasn't?), you’ve undoubtedly used the Ctrl-Alt-Delete key combination to force the program to quit. Unlike PCs, however, OSX doesn't use the typical Ctrl-Alt-Delete key combination to Force Quit frozen programs. If an application hangs up on you on your new Mac, just follow these simple steps:
1. Press Command-Option-Esc on the keyboard to open the Force Quit Applications window.
2. Select the program you wish to terminate and click Force Quit.
3. Click the Apple logo in the top left corner, select Force Quit from the drop-down menu as an alternate method.