League crashes and won’t reopen?

Hey guys, for a couple weeks now, I’ve been having a problem with League where after the champ select process, once it’s supposed to transition to the loading screen, the game never pops up. I try to close the client and reopen it and try to reconnect, but it won’t let me. Then the only way I can play it again is if I restart my computer. It’s been causing me to lose a lot of LP, because it doesn’t happen every game, I never know when it’ll happen. I also don’t know if it’s a problem with the game itself, or the computer, but it doesn’t happen to any other game.