I know that the country list box detects the user country based on IP range, it uses the GeoIP.Dat file. It never worked for my website. 
I live Brazil and I asked some friends from London (UK), Los Angeles (US) and Sydnei (AU) to test the site. They told me the same problem ocurred.
I thought that the problem could be an outdated .dat file. I updated it and the problem continues.
There is something I have to configure?
Thanks