Having an issue with playing co-op in Chaos Theory on XBOX Live with the following setup:

I have:
original XBOX (NTSC-J)
Chaos Theory NTSC-J version

friend has:
XBOX 360 (NTSC-J) with all of the CT related patches downloaded
Chaos Theory NTSC version (region free so it boots fine)

I can invite him and he joins the lobby session fine with chat working but once we load up the scenario and the host presses A, the game disconnects everytime.

I would appreciate any advice.

And you will continue to have issues with that. The game is very hardware dependant on the co-op side.

The versus side seems to work okay however.

Both modes were actually coded by different groups, and to overcome some of the difficulties of player interaction in co-op they did some kind of work-around that made it not work cross-platform.

Thanks for the reply. So if we both use the same platform (ie XBOX-XBOX or 360-360), there should be no issue then?

That is correct, the same consoles should connect with <few> problems.

Occasionally you could still drop a connection, lag, etc., but at least you will be able to get past the first 3 seconds, LOL.