[CLIENT] New League Client won't open. (Mac)

Alright, so I played a bit earlier today and then quit it to do some work. When I tried to reopen it later today it said that "Another instance of league client is running. please close it and try again." Now here's the weird part, league client wasn't open. I went into force quit and it said that league client wasn't open. I had to shut down my computer and turn it on for it to work. This never happened before I downloaded the new league client beta so I'm pretty sure its something to do with that. Any help would be really appreciated.