CANCEL YOUR DISCOVER CARD NOW. I had the same problem. I could not sign on and they said they were sending a new card (without giving a reason). Yet they are STILL HONORING bogus charges on the old number (the one which THEY KNOW has been breached) and expecting me to call them to discuss the matter. I have cancelled my card with them and strongly recommend that everyone do that. Visa, MasterCard and American Express know how to manage their security (they would stop honoring charges to the old number) and they value customers (they would not put the responsibility on ME to fix it). Discover seems to see customers as the product that they wrap and sell to their merchants: They seem to see the merchants as their customers (since they have many fewer merchants than Visa, MasterCard and American Express).