Black Ops Online Problem?

So a couple days ago, CoD Black Ops will not let me join games. It always says looking for lobbies then sends me back and makes me a host which never gets any players. When I do get in games I have the poorest connection possible. My Xbox says I have full bars from my wi-fi, all the computers in the house have speedy internet, even the market place on the xbox dashboard works. Could my $100 black duel pronged xbox wi-fi thing messed up? ps. I normally always have incredible connection and my NAT is open