Try (alt-tabbing) or running the game in "windowed-mode".  Sounds to me like a firewall is asking for permission to allow SINS outbound traffic!

Also how do you run it in windowed mode. If it makes any difference i have Vista.

look for my post does it have anything to do with impulse updateing recently ? if so i have a post but the game things its due to memory read/ write even if you can play game for over an hour on a game and then host your own and crash

alt+tab should give you the error box and what it did .dmp file in documents and settings look it up, see if you can find one for sins. thanks