[Crash] Game crashing at about when the minions meet

So, it's been 2 consecutive games where the game window crashed. Both of them were at about the same time: when the minions meet for the first time after "Minions have spawned". I'm not sure what's causing that though, as I've played a couple of games today, but only the latest 2 had crashes. The crash didn't close the LoL client, just the gameplay window. I am using a Macbook Pro, 2.5 GHz Intel Core i5, 8 gigs of RAM and an Intel HD Graphics 4000 video card. Hopefully this doesn't happen again. Thanks. :)