I'm guessing it is a firewall problem. If you just have Windows firewall, try turning it off (temporarily) using the instructions found here:
http://www.utmem.edu/helpdesk/sp2/sp2firewall.htm
If that still doesn't work, I suggest trying from another computer, maybe even one in the United States to see if that helps. Create an account with a password that you don't care who knows, and give it to one of your friends in the US. Try and get them to validate it, and see if you can log on then. This may just be a one-time problem.