Using the correct term gets us half way to a diagnosis: kernel panics, freezes, app crashes and unresponsive apps are distinguished here.
freeze
What to do when your Mac panics during booting, and enters a boot loop, or when it simply fails to get to the login window.
How to tell apart unexpected quits, WindowServer crashes, kernel panics, and more – and what to do about them.
What is wrong when, out of the blue, the display freezes for ten seconds, then you see a black screen and are asked to log back into your account? Malware perhaps?
Knowing the difference helps you work out what to do in response, and how to work out what went wrong.
What they are, how they’ve changed, how to work out what went wrong, and how to deal with them. No Mac should ever experience a single panic.
Had my Mac frozen, or was it just very busy running tests on the boot disk? When I forced it to restart, what did the log reveal?
Is there anything more irritating than that spinning coloured wheel, or beachball, which stops you from getting on with a task? This explains why, and what to do about it.
Can you tell the difference? What is the significance of each, and do you know what to do about them? An introductory guide.
From 10.8 onwards, you will not see the classic grey display, but your Mac will spontaneously restart or shut down. Here are the details, and what to do next.
The Eclectic Light Company 