Game crashes and then low priority.

For the past few games I have crashed in the first fifteen seconds of the game for no apparent reason. I try to reconnect, but it won't work and I just get 5 low priority matchmaking waits for 20 minutes. If these stack I will currently have 15 20 minute wait times because of my game crashing. My computer can easily run League, so why is it always crashing? Any help would be appreciated. The things it says on the support page isn't very useful.