Client crashes

So i got a PC and installed League and it worked just fine, until it suddenly began crashing, the weird part is it's followed by a massive lag then the crash happens. It's usually around 8th or 10th minute of the game, i have no other problems but this one. It keeps getting on my nerves cause i have to afk for about 2-3 minutes from the game and i usually die to the enemy laner because of it. Any solutions for this? p.s. I have two more friends with the same problem so im not the only one.