QUOTE(metaldevil @ Dec 31 2005, 01:28 PM)
If you're confident that it's software-related, then here is what you should do:
Take your receipt, 360, unscathed (no scratches) DOA4 game and the games that work properly to the place of purchase. Ask to speak to the manager to prove your point that it's software-related. Play games on your 360 to show him that it works fine. Show him that the DOA4 has no scratches/fingerprints on it. Then, insert DOA4, and show him where you can't play as Kasumi. Once you do, I'm fairly certain that he will show some compassion and allow for an exchange.
You're kidding right? There's no need to bring the 360, any decent store will take the game back and give you another copy if you say it doesn't work.