CLIENT- corrupted files mid-game?

league up and crashed in the middle of a match, gave me the usual song and dance "have found corrupted files blah blah" and did the little 5-10 minute "fixing" corrupted files load. this is the 2nd or 3rd time in the past week i've gotten the corrupted files notice, but first time its happened midgame, which i feel like shouldn't be possible, but what do i know. anywho i have cc cleaner/defraggler and such and have re installed league after the first corrupted files notification. why is this still happening?