7.4 PATCH black screen

I am not the only one who have this problem. My computer delays several seconds after i click "acepter a game", also there is black screen before the results occuer in the end of game.

Now i cant get my wanted position in normal game, I can basically always go play support, because others never want to play support.

This affects so much my experience of game.

Each time I enter the chat of game, they have already declared their position.

This only happens after the upgrading of 7.4 patch.

Plz figure it out riot.

Not only my problem, it is not about my screen hard drive i think.