User blog comment:Conqueror of all Zombies/Multiplayer Help/@comment-2257548-20100822061724

Well, it could be that the server is having trouble right now-- it does that sometimes. Usually when that happens it just stays on the loading screen forever.

If you're on Xbox Live, and it says something about "connectivity issues", you may have problems with your NAT-- it's something to do with your ability to communicate with other Xboxes. xbox.com/support has some tutorials on how to change your router's settings to fix this.

Can you give any more specific information about what's going on? What system are you playing on? What happens when you try to connect?