Team Builder bug [CLIENT] [CRASH]

Whenever I join someone in Team builder or try to make my own team, as soon as I click Join/Create game it makes me play as malphite. I can switch lanes, masteries, runes, and summoner spells but I can not change my champion from Malphite. If I do try to change to a different champion my client crashes and I have to go into Task Manager and end the task. This gets very annoying when I want to play team builder with friends but can't switch from Malphite.