[CLIENT] I cannot see party chat, arranged team chat, or champion select chat

Whenever I am in a lobby with my team (before we have entered queue), in queue (the automatic 5-person chatroom that appears during queue), or in Champion Select mode (normals and ranked are both effected) I cannot read chat at all. I can type and my teammates can see it, but I don't see my own chat or anyone else's chat.

PMs work fine and there's nothing wrong in-game. I have reinstalled the game twice and the problem has persisted.

Edit: Can't see post-game chat either (the 10 person chat after the game ends), if that helps determine the source of the problem.

OS: Windows 7 64-bit