Having problems with LoL client

Briefly said, when I start up LoL client, it takes more time than usual to load the starting menu. Then, when I click the 'confirm' button, it goes gray and does not start searching for a game. Could this be an issue with the broadband/data transmission? I am from Bulgaria and this happened the previous week and I was not the only one experiencing this problem. There were only major delays when I was in champion select, but now the game is unplayable, because I cannot start searching for a lobby.

I reinstalled LoL, but the problem is present. I will gladly listen to any suggestions and provide further information, if required.