This has happened three or four times now and at first it was only present on Ahri but now that it's happened with Soraka i'm convinced it's purely down to the star guardian skins.
Each time i get a game with a star guardian skin, i enter the loading screen and it begins as normal. Then, about half way through load in, the screen closes and returns me to the client with a 'reconnect' button, same as when you leave a game in progress. This means that whenever i use a star guardian skin i am forced to start the game 5 minutes late.
I have included a screenshot of my system specs, hopefully this issue isn't isolated and riot are or will work on it quickly.