Session No Longer Available

So the story goes as this, I set my home on my brothers xbox, then decide to return it to my own xbox. Then I get a pop up that says that it's having problems starting up or that "The person who bought this needs to sign in." But I'm the person who bought
the games and none of them work, Im unsure of what's wrong. I then check my network to see if that's the problem, it says I'm having problems with "Purchasingredients and Usage Problems" it says that I have session issues and idk how to fix that.

:)

 

Disconnected: Session no longer available.

The game has since been updated and patched to fix this problem.

 

Disconnected: Session no longer available.

Here is the story.

We have one xbox 360 and have really been getting into the Left 4 Dead series. We decided to get a second one so we could play with all four of us via system link. The game was already installed on xbox #1 (the older, white one). I bought the Slim 4gb
xbox (xbox #2) and another copy of L4D2 yesterday. Then we connected both xbox's with an ethernet cable.

From the L4D2 main menu we went to versus -> play with friends -> create game (on xbox #2).

On xbox #1, we went to versus -> play with friends and could see the lobby on #2.

But when we tried to join, we got the error "Disconnected: Session no longer available."

It is obviously passing data back and forth over a standard ethernet cable, so I can only assume it is auto-sensing and a crossover cable isn't necessary. So I did some googling and found out that it might be a storage concern and the 4.4gb game might need
to be installed to play this way. So I picked up the 320gb drive today. I added that to xbox #2 and installed L4D2 on it, and we still got the same error.

So then I wondered if it was a version error between both games even though I don't remember either of them being patched at any time. I deleted everything L4D2 off of both machines and reinstalled. And I still get the same error.

I don't get it. The only physical layer equipment between the 2 machines is a CAT5 cable. The latency is probably about nil. The two machines are obviously talking as I can see any lobby created on the other machine, but it won't let me join it.

Unfortunately, this is the only game we have a duplicate of, so I can only test with it. I don't get it... Is there something I am missing?