Champ Select Unkown Bug

About 5 minutes ago, I was in champ select for my 2nd game of a series, and I got a really intrusive error. While the enemy team was in mid pick, I got a message saying unknown error occurred, and I was subsequently booted from the lobby for failing to pick a champion, costing me a game of my series. Can anyone tell me what that was? And is there any way I can be given that game back? I am 1-1 now in the series so it is not lost, but it's absolutely absurd that I have to eat a loss because of an error in the client that has nothing to do with my computer (as far as I know).

As a side note, the whole client is now running very slow following that error, and I can guarantee it is not my computer (fairly recent custom build with no virus's/malware ect..)