I tried to connect to "Play online" and got this message: "The action cannot be executed : the version of the game is not supported."

What is this? The game was working fine yesterday.

Is it a problem at the server end?

I belive this is due to the patch. Try starting the game again and seeing if it will DL. If not is this section of the forums you can find the details to do a manual DL of the patch.