My xbox 360 froze what do i do?

i turned it on and it was taking longer then normal to sign me in and then sead something like you cant acceses al of xbox live and when i went to play halo3 on match macking it said it wasnt connected to xbox live so i tested it and it was fine so i went to play again and it froze so i turned it off and tryied agin and it still took a long time to sign in and it will not connect to halo 3 xbox live whats wrong?