I was playing black ops 2 earlier today then I got off xbox. When I got back on It told me to enter my email and password (first time I ever had to do this). Then it said that my email and password do not match. so i went on xbox.com and changed my password and it didn't work. I then changed my password again and it still didn't work. So I read that if i clear my system cache and redownload my profile then it would work. But it still pops up error 8004821. Really annoying i've been trying for at least 2 hours to get it working. And i know my password is right because I just logged in to post this.