How to fix random total freezes?

[nmaxcom]

This has been hapening for a couple of weeks, 1-5 times a day it freezes completely, the screen stays the same (doesn't even turn off when closing the lid) and is completely unresponsive. I have to force shutdown and restart.

I can't figure out what it is or could be, haven't detected any patterns, time of day, activity, etc.

How can I track this down?

 

[Fishrrman]

Which MacBook?
What year was it made?
Which version of the OS?

 

[nebojsak]

I had this behavior with failing graphic card in my old MacPro.