Client black screen in champion select.

So, I've tried to enter a game, I entered a queue and then proceeded to look at something on youtube, when a match was found, i accepted then looked on youtube again, when I looked at lol again, it was black. It is not very consistent but it happens sometimes and it makes you lose LP. Step by step:

1. get in a queue
2. minimize the client
3. accept the match and minimize again
4. maximize