Constant Disconnections at Game Start

In probably 1/3 to 1/2 of the games I play, I get disconnected from the server as soon as everyone has chosen their champions. Sometimes it will allow me to reconnect, but a lot of the time it won't let me join the game no matter what and penalizes me for it. My internet is not the problem, because I have absolutely no connection interruptions with anything else, and can even still connect to the LoL home page if I exit and restart the client. Does anyone know how to fix this? I found a post here about disabling the IP service or something, but I did that and it didn't seem to help at all.