Mac won't start
Before I start, the issue resolved itself somehow after several attempts but I wanted to know how.
As I entered a game in League of legends approx 4-5 min in game with youtube music playing in the background my late 2011 macbook pro suddenly showed a striped screen and did not pick up any of my inputs (i.e. Command tab, Command q etc.) So I was forced to shut down my mac and turn it on normal mode finding a pixelated white screen, normal chime with the apple logo and loading bar. after the astonishing 15-20min wait it comes up on a plain white screen. I repeated the same process even with safe mode on and it just wouldn't let me go on to the login screen. So I gave up went for about 10min leaving my mac on the plain white screen it stays on. Coming back, i find my computer shutdown for some strange odd reason so I turned it back on in safe mode just in case. A normal startup apple logo came up for quite some time and then when straight to my login screen. working perfectly. I restarted it and started using it as per normal running some disk repairs.
Does anyone know what could've caused this stressful issue, and why it happens? Should go I keep playing this league of legends game for my mac's safety?
Macbook pro 15inich late 2011
2.2 Ghz Intel core i7
4GB Ram
Intel HD graphics 3000
hard drive is not even half full
Thanks much appreciated for an answer.
MacBook Pro (15-inch Late 2011), OS X Yosemite (10.10.3)