Occasionally no keys will work after loading into game

Every once in a while, when I load into game, none of my keys will work. I cannot open the shop by pressing 'p'. I cannot open the score board by pressing 'o'. I can't cast either abilities or summoner spells.

I don't know what causes this bug or how to replicate it.

In my experience the only thing that works is reloading the game, though sometimes even that won't work. Recently I had a game where I tried to reload the client three times and it had no effect. To get my game to function properly, I needed to restart my entire computer and then reload the client.

This is getting extremely irritating.