Why does my smart cast randomly turn on?

Occasionally ingame, I suddenly am unable to click P to shop, Esc for settings, or Y to unlock screen. Additionally, I can't click the Buy button in shop and all my abilities become smart cast and I am unable to move once I hit someone until I use a spell, I die, or the target dies. I find it extremely toxic to play and I don't know the cause so please, help me Riot.