Online Probs

[ImportR]

I have been desperately trying to play online, but either no games show up on the list (I've messed with the Filter setting) and/or if I manage to start a game and someone joins, I click Start Race and it sits there and comes up saying Game Session no longer exists. I have no firewall or anything of that nature. I played the demo the same way and it worked fine. I haven't had 1 online game yet because of this. Anyone have a clue?