Gremlins. Invisible little nitters are messing with your drive.
In seriousness, there's one thing that's always true: computers can be the pickiest, most finicky things on earth when things aren't just right. Either there is a bad component here which will eventually show itself clearly or there was some little thing messing up what should have been a smooth process (since I can see nothing you obviously did wrong anywhere, and no compatibility issues either).
Either way, hope for the best. Let us know if it goes through!