I'm one of the few apparently who is not able to connect to the servers. I called 1800-4my-xbox and the tech support guy had me re-download the latest system update. It worked for like 5 seconds and before I could select a match it brought up that error again. It might work for some people though. All you have to do is go to system memory and before you select a device you press:
left bumper, right bumper, x, left bumper, right bumper, x.
This should prompt you asking you if you want to delete the latest system update. Just say yes, re-download the update and hope it works. Other then that xbox tech support said to come here. lol.