Broken leavebuster

The game is going fine, however, my pc crashes at around 6 minutes, I come back at around 12 minutes, we finish the game, I have good score, game lasts around half hour. YET I get a 20 minute leavebuster, minus LP and a D- mark, now can someone tell me how does this make sence and if there is any way this pentaly could be removed from me now?