

It’s highly recommended that you ensure Mac OS and all your applications are up to date, because regular updates should fix critical performance, security and compatibility flaws in Mac OS and your apps. A failing hard disk would likely contribute to system freezes and crashes. status of your hard disk, which will highlight any potential problems. Also in Disk Utility, you can check the S.M.A.R.T. This will highlight any hardware issues that may be contributing to system problems. If you have already set your Mac to restart automatically when an unrecoverable system freeze occurs (in the Energy Saver control panel in System Preferences) it should restart by itself in such circumstances In these cases there’s very little that you can do once the problem occurs except force a restart (hold down the power key for a few seconds).

System crashes/freezes, when the whole system has become slow or totally unresponsive and you can’t even use the mouse or keyboard.

In these cases it’s usually possible to force the application to quit (hold down CMD + OPTION + ESC and choose the application) if it hasn’t already done so, and then continue to use your Mac normally
