[GAMEPLAY] Game-breaking bug!! Holding any key causes LoL to freeze until that key released

When the game started, I was running at a very low framerate, much lower than normal. Then I realized that if I held down ANY button on the keyboard for about 0.5s, League would hardcore freeze for until I released that key. Space, tab, control, Q, D, 4, anything at all (mouse buttons didn't cause freezing, tho). I restarted LoL once, hoping to fix the bug, but when it was still there I started recording with Fraps; the audio desynch/distort is probably due to the freezing. Even the FPS counter from Fraps froze when I held a key while recording. I restarted it a second time and the bug persisted, but about 30 seconds after the 2nd restart, the bug magically fixed itself.

This is the 2nd time I've ever had a bug like this; it very rarely happens when the game is loading and something goes wrong, I suppose. It might be worth noting that the Zac on our team was AFK at the beginning of the game, as well as the enemy Viktor (maybe they had the same bug, maybe it was unrelated, they didn't say).

This is the match overview page: http://matchhistory.na.leagueoflegends.com/en/#match-details/NA1/1837204400/227160860?tab=overview I doubt it will be helpful, but I might as well include it.

If someone from Riot requests any logs from my game, I'll edit this post and add them.