Most application crashes in Mac OS X will not bring down your entire system, nor will they require you to restart your Mac. Thus, in many cases the cure for an application crash is to simply ignore it, relaunch the crashed application, and hope the crash does not occur again (or at least happens only rarely). If this is not sufficient, consider the solutions described in the following sections.
Freeze/hang
Applications occasionally stop functioning often while attempting to perform some action, such as opening a document or receiving an e-mail. In such cases, the spinning wait cursor appears and just remains; the intended action is never completed. At the same time, attempts to otherwise interact with the program (such as choosing menu commands) also fail to work. This is your standard application freeze.
Occasionally, issuing a Cancel command (Command-. [period]) will end the hung action and return control of the application to you; however, there is only rare success with this technique in Mac OS X. Also occasionally, waiting and doing nothing will succeed which means the application was just taking an unusually long time to complete its task. More likely, though, something has gone awry, and simply walking away from your Mac won't fix it.
The silver lining is that the effects of these freezes are almost always limited to the affected application. That is, if you simply click the window of another application, the spinning cursor vanishes and your Mac is working normally again. Return to the problem application, and the symptom returns. Still, on the assumption that you would like to use the frozen application again, you'll want to fix the problem. To do so, try the following:
Force-quit the application.
If force-quitting doesn't work, but you can still access the Apple menu, choose Log Out from there. When you log back in, things should work normally.
If the Log Out command doesn't work, try choosing Restart. The logic is the same.
Occasionally, an application will fail to launch, leaving its Dock icon to bounce endlessly. At this point, it's possible that no menu commands will work. Even so, you should still be able to force-quit the application.
Systemwide freeze
Occasionally, a frozen application will cause the entire system to hang that is, you get no response from any application, the Finder, or the Dock. In addition, the pointer may no longer respond to the mouse and the Force Quit command fails to bring up the Force Quit window. When this happens, there's typically been a freeze or crash of some critical process, such as login window.
Two well-known cases where you may get a systemwide freeze:
File sharing. If an attempt to connect to a server is unsuccessful, or if you are unexpectedly disconnected from a server from which you had already connected, a systemwide freeze can occur.
Web browsing. What starts as a simple failure to load certain Web pages may spread to a systemwide freeze. The most likely cause is the freeze of a process called lookupd (used to match network domain names to their IP addresses).
If you can still get the Force Quit command to work, force-quitting the Finder (and/or your Web browser) may be sufficient to get things working. If the freeze has not progressed to the point that you can no longer use Terminal, you may be able to fix the problem by killing and restarting the lookupd process. Otherwise, disconnecting and reconnecting the network hardware (such as a router or cable modem) may work. As a last resort, you will need to hard-restart/reset your Mac.
Force Quit The Mac equivalent of CTRL-ALT-DEL to bring up a system tasks profiler for force quitting unresponsive tasks is CMD-OPTION-ESC (or Windows-ALT-ESC if you are using a PC keyboard). Just select the frozen application and hit Force Quit. If a program is completely frozen, it will appear in red text.  |