screen freezes during champion select

many times durying champion select ( both blind and draft ) my screen freezes and prevents from picking a champion because i cant click anythink durying that time period .Also it apears to happen before i even join the champion select ( the time period after i accept que) also preventing me from picking a champion and leading me to get a ban .I have tryed may thinks and followed many defrent opinions to try to fix this problem but nothink worked .Riot plz fix this problem because it make sthe game unplayable