Mac crashes are rare, but they do happen. So what should you do if you experience a crash on your Mac?
Sometimes apps freeze. You won’t even be able to quit the app and the spinning wait cursor will appear -- a colourful circle known informally as the pinwheel or beachball of death.
Wait for a moment to see if the app recovers. If not, the only choice is to terminate it -- hold down Ctrl and click the app’s icon in the Dock, then select Force Quit. If you don’t see that option, hold down Ctrl and Alt together, then click the Dock’s icon.
Sometimes a single “force quit” isn’t enough and you might need to do it twice or even three times.
Try repairing disk permissions to avoid future crashes – start Disk Utility (it’s in the Utilities folder of Applications), then select your disk on the left and click Repair Disk Permissions.
An app might unexpectedly disappear and a dialog box pop-up saying the app has “quit unexpectedly”. If you reopen the app your work might’ve been saved – particularly with Apple’s own apps like TextEdit.
System app freezes
If the Dock itself has frozen, hold down Alt and Cmd and then tap the Esc key. This will show the Force Quit Applications dialog, where you can select any app and click the Force Quit button. Alternatively, hit Cmd+Space to open Spotlight, then type Activity Monitor. Hit Enter to run it, then select the app in the list and click the Quit Process button. Then click Quit in the dialog box. If the app doesn’t go away, repeat the step and click Force Quit.
Sometimes the Finder will freeze. If this happens the desktop will also become unresponsive. The same Force Quitting options as above apply but first try holding down Ctrl+Alt, clicking the Finder icon, and selecting Relaunch.
If the entire system appears to freeze then try holding down Shift+Alt+Cmd and Esc for around five seconds. This will Force Quit the top-most app that’s causing the jam. If the system remains jammed, you can force a reboot by holding the power button for five seconds to power down, then pressing it again to boot as usual.
A kernel panic happens when something has gone so badly wrong that the Mac simply can’t continue working. It sounds more severe than it is, however, and the chances are your computer will reboot and return to normal.
With OS X Mountain Lion the Mac will reboot and then you’ll see the following grey text against a grey background: “Your computer restarted because of a problem. Press a key or wait a few seconds to continue starting up.”
Kernel panics happen for all kinds of reasons and are usually not a worry unless they happen repeatedly. They often indicate hardware faults, such as problems with the RAM or hard disk. You can check the health of your hard disk by holding down Alt and clicking the Apple menu, then selecting System Information. In the window that appears, select your disk from the list and look underneath at the heading that reads S.M.A.R.T. Status. “Verified” is good. “About To Fail” is bad.
Memtest will test your Mac’s RAM but sometimes a visit to the Genius bar is the only option.