Or it could have just been flaky encoding. Back when I used to use Audio catalyst, if I tried two encoding sessions at once putting the files in the same directory across a network this would happen (yes encoding music to a network drive is a bad idea, it was a long time ago, I know better now) .... don't ask me how... all I know is I had Soundgarden's "loud love" intermingled with Lard's "Mate Spawn and Die", it did this to several tracks a few seconds of one song, a few minutes of the other. What sucked is that I'd encoded so many songs without checking them these little jewels were scattered throughout my entire collection...