Bump
I've been having this issue for quite a while to. As far as November that I can remember. I think OP gives a good explanation of what happens to me. Not sure if it's for the same reason.

Same problem as I'm having sounds like.

FIX THIS.

I have been having similar issues ever since the preseason 2 balance update. I really want to play the game but now in 90% of my games I am freezing and then have to restart my computer in order to get it to respond.

Any advice would be wonderful.

I have been having the same issue, sometimes I can play a few games without a problem, sometimes the screen turns black, sound starts looping and the only way to get things back to normal is to turn notebook off the hard way.

I have tried with lowest graphic settings
Re-installing lol
Fromating
Updating drivers
Cleaned the fans and checked temperatures, not the issue.

No other game gives me this problem
Problem has been consistent in windows 7 and 8.

Video card: gtx 285m
6gb ram ddr 3
Processor i7 1.73

This started happening after an update, I don't remember which one.

haven't bumped this in a while because the forum logons were busted (LOL). anyways this has been A LOT worse the past few days, I think I have crashed in upwards of 50% of my games the last few days (which have been very few in number because of this), while the last few weeks/months it's been more like 1 in 20 games that would crash.

At this point I'm just hoping to find more people with similar experiences and not an actual tech support answer.

Bump happens to me too but i bet riot wont do **** caz they dont like to help out the lil guys