Let's make sure that you have forwarded your ports properly:
The first link that I provide you with will take you to a piece of software that will let you test your port numbers to see if they are open:
http://portforward.com/help/portcheck.htm
The second link is to a free program that will set a static IP address for your PC:
http://portforward.com/help/setup_static_ip_address.htm
The third link will take you to guides that will walk you through the port forwarding process:
http://portforward.com/english/routers/port_forwarding/routerindex.htm
Here are the port numbers that should be opened:
UDP: 27000-27015, 27015-27030
TCP: 27014-27050.
If you are prompted to purchase anything, there will be a link in the top right corner of the page that says, "Skip this advertisement..." and you should be directed to the proper page after clicking that link.
Once you're done with all that, go ahead and restart your modem/router and your PC.
