AfroAmErIcaN216 and Primal Gravy, these forums work best when you create a new thread with a first post of your own, as the original poster's problem and solution, although similar, could be very different in detail. It's great that you're researching here, but the quickest path to a solution is your own thread. Please start your own with a new port in Forum 03, http://forums.xbox.com/xbox_forums/xbox_support/f/12.aspx . That being said,
0) If any of these steps to do on a PC or Mac shows you a message about a Blocked Account, please follow the onscreen instructions to Unblock it.
1) Go to http://account.live.com and sign in then go to Edit Security Info. Is all data there up to date? (If not, please update it).
2) Go to http://xbox.com/accounts to click on Billing Contact Information at low left and sign in. Is all data there up to date? (If not, please update it).
3) Go to http://commerce.microsoft.com and sign in then review the payment info. If there's an out-of-date card or PayPal account, please add a new payment method then delete the old one.
4) Back to the console; can you sign in there now?