ok lets see what we can do

So the port forwarding works when you send it to one computer but doesnt work on your computer. So we know the problem is your computer and not the router that's good.
On the main computer make sure the windows firewall is running and turned on. Make sure to add the ports to the windows firewall as well.
Double check that your main computers local IP is the right one in the port forwarding rule.
The problem may lie with the windows firewall not working right, I have seen that happen with another person.
Let me know
Shane