Youtube in Safari cause system crash Regarding MacBook Pro early 2011: sound loop, black screen

It happened again and it's the 5th time in one month. Everytime I play youtube videos on Safari only the screen just freeze and the fan gets much louder.

I forced it to shut down and when I turn it on again I got black/grey/blue screens..

Is the Flash Player the main source of problem here? I updated it to the latest version.
First thing I would always try for Flash issues is to disable Hardware Acceleration...

Right click any Flash video &amp; select Settings...



Then click the first tab at the bottom &amp; uncheck Enable hardware acceleration