Halo 3 Matchmaking Not Working?

[Kiera]

It won't load the playlist in Matchmaking on Halo 3 on Xbox LIVE.
And it says "Imformation could not be retrieved from Xbox LIVE."
I've tried restarting my 360, signing in and out, and switching lobbies.
Nothing's working! Please help.
Thanks.

 

[Vio 07]

Check your modem connection. If anything isn’t plugged in all the way or your internet is down you would be able to access live. If you use an Ethernet cord be sure it’s in good working condition. Press (X) in matchmaking to look at connection options as well.