Impostors, eh? I'm pretty curious to see where you're taking this story. It's already obvious that Harry is essentially unstoppable to wizards, but I'm more intrigued about the impostor Hermione and Mr. Granger and the whole situation with George. Pretty far out there compared to the rest of the story, isn't it?
Chapter 4 has some issues. You might want to start checking every chapter over immediately after submitting it to avoid this sort of thing.
Imposters? What imposters?
I'll look at Chapter 4...
Chapter 4 (and Chapter 10 fixed...)