Debilitating TFT bug freezes my PC, please respond Riot.

Earlier tonight I was playing a TFT game and as the game progressed it was obvious my game was a losing one so I decided to restart and get into a new game by surrendering. When I clicked on the surrender button the game black screened, froze, then became unresponsive. I then decided to alt-tab to execute the problematic application in the task manager. When I went back to log into league of legends the client was bugged and stating that the client could not connect me with the servers and that I should check the server status or follow the steps to repairing the client. I initiated a full repair on the client, which solved the log in issue but now the game automatically launches me back into the old (30 minutes since) TFT game where it black screens, never loading me in and prompts a windows page stating the program (League of Legends) has encountered a critical error and needs to be terminated. The thing is the black screen locks my pc and does not allow me to alt-tab, nor bring up the task manager to execute the program. Meaning I need to restart my pc in order to get it back from the bugged program. I've opened it 3 times now, the same issue persists even though I know for certain that game is most likely over.