[CRASH] My client crashes whenever I lock in my champion in Ranked, and only in Ranked.

I thought this was an isolated incident when it happened last night, but then it happened again tonight. When I lock in my champion in Ranked, my client freezes and crashes. It hasn't happened to me in Normals at all, and in addition to crashing, when I am in Ranked champ select, my client gets - for lack of a better term - super wonky. The names of the players leave the screen until it's their turn to pick/ban, and my runes, masteries, and summoner spells are all invisible until I hover over them. (Probably the runes, etc. are also off-screen. I say "off screen" because I can just barely make out the names of the players and the "Ranked 5v5 Draft Pick" text at the bottom left of the client behind the chat window, then they pop back into place when that person is up to pick/ban.) And then the aforementioned crash upon lock-in. Last night it simply gave me the boot from the lobby and gave me -3LP for dodging when it crashed, though today I could reconnect and play if I relaunched the client. I'm not going to risk trying Ranked again tonight, so as to avoid the risk of more negative LP, but I know y'all folks at Riot can probably help out, so thanks in advance!