Some keys not registering

I have NO IDEA what happened, and I don't know how to recreate it. But randomly one game, I couldn't Q, R, or B. I Maybe even other things I couldn't do. I checked my hot keys, everything's as it should be. I typed something with those keys, they worked fine. I checked Quick Cast, it's fine. THEN. After the game. I made a custom to see if things were still messed up. Nope, everything's fine. What happened? I was playing Kat, if that helps at all.