Disconnecting from xbox live

Guys once i start halo i keep disconnecting form xbox live and i can not play halo online can some one tell me plzz what to do and how to fix it plzz ^^

I would try Xbox support if I were you.

http://support.xbox.com/en-us/Pages/default.aspx

It happens some times, turn of your Xbox and then turn it back on shoulde help.