Sorry for the late reply.
Basically what happened there is that one of the Parts got mixed up a little when you downloaded it. (Most frequently, Part 2 ... if anything gets corrupted, it's usually the largest files like data.grf)
Move or delete Part 2 (the first .bin file) and download that part again. I would recommend using a wired (rather than wireless) connection.
I'm kind of hoping they set up a torrent file soon because i always had better luck with that.
