i've never seen this error before, have you tried going to the xbox website and seeing if it says anything about the error there? Otherwise you could always contact their helpline, where thats of any help though is another matter as they may have a bunch of people just reading off prewritten sheets. Email could be a good option as you can describe to them exactly what your problem is and hopefully they can give you a good answer

I don't know when this game is coming out but for the old skool fans TIMESPLITTERS !!!!!! Don't forget this game because it had to be one of the best games ever released on the PS2 and the graphics on Future Perfect for PS2 were quite impressive! If you go to Free Radical Design you can see that TIMESPLITTERS 4 is in the works!!!!! Maybe not this year but the year after? It can't be to far away. Hopefully it will be released on the xbox 360

This company developed the game HAZE for the PS3.

http://www.frd.co.uk/timesplitters4/index.php

I wouldn't have thought that it should limit you from the marketplace. That's quite odd, i know in the past some of my friends have had troubles with having scrict NAT and i think there may be a way of changing it, at the moment mine is moderate but i seem to always be able to join to almost anyone.

I've found a past thread which may be of some use, otherwise try searching around on the internet a bit, its sometimes quite easy to find a solution, if you don't find anything i'm sure there will probably someone with some good knowledge on it on the forums. If i manage to find out some more information i'll let you know.:D

http://uk.gamespot.com/pages/forums/show_msgs.php?topic_id=25828687&page=0&prev_button=1

Past Thread may have some good info in?