We have an issue with an ex-family pack account. Whenever my cousin tries to log in he is asked for his email address and password. He puts in the correct one (it's working fine on xbox.com) and the console says that the details are incorrect. After this he either has to try to enter the password again or back out of the pop up window. As his password is never accepted, his only option is to back out, but this step signs him out of Live.
He already tried deleting his profile from the console and his system cache and then download the profile again but he is still getting the same error message.
We also tried and succeeded to change the password of the account, but the new password is not accepted either.
Is there any other workaround to solve this?
update: the issue seems to be similar to this one: http://forums.xbox.com/xbox_forums/xbox_support/f/9/t/1528458.aspx but the solution there isn't working for my cousin.