when i try to sign in to xbl popup says cant connect to xbl asks if i want to test connection if i wait and say no do not test connection it will sign me in to xbl but console runs so slow that it almost freezes up but if i sit and wait fifteen mins. it catches up to itself and than does the same thing next button i hit i try to play halo 3 and it says i need to install an update to play online i try to download it and it tells me my console can't connect even though i'm already signed in to xbl any suggestions would be greatly appreciated

Try to do the connection test.... sometimes juts drag the ethernet cable out of the modem and wait 30 seconds pop it in and restart your 360.