Riot games Client crashing?

Past few days my game keeps crashing while ingame lobby (champ select) and it keeps happening , hasnt really ever happened before up until a few days ago and i have "dodged" about 5 times because of it ? does anybody else have this problem or know a fix? My friend has also been having the issue where it freezes when banning a champ and it wont let him ban anything and he dodges because of it. thanks plz help find fix. rip my lp