If you're just starting a game out and after finishing naming your character, you hear Hadvar say "Who are you?" a second time... it might be advisable to go back to the beginning and retake the wagon ride.

Why? The game when Hadvar asked "Who are you?" AFTER my character's creation is the game where the golden claw door in bleak falls barrow could not be opened, the outer three rings could not be moved. See here: http://www.gamesas.com/topic/1398270-main-quest-killing-glitch-at-bleak-falls-barrow/page__fromsearch__1

How this glitch is implemented? Customize more than one character in character creation before choosing.

I'm on the 360, with Dawnguard installed on a secondary memory chip via USB port. I also have the full installation of Skyrim on this memory chip, making the game run smoother.

If someone can verify on this please reply.

I don't think so, lots of people start a new character from the who are you point because they have seen the wagon before. I would try going out of the cell then going back in or reload an earlier save.