I think it also has to do with cookies found on your machine, but I'm not certain. I use the TOR network a lot, and when I'm browsing with TOR, I get exit nodes all over the world - Europe, Asia, Australia, South America, Africa, you name it. Now, I never use Google on the TOR network, but nevertheless, Google often seems to somehow think I'm in the Ukraine or Japan or whatever, and when I open up IE my home page (which is Google) defaults to that country's version of Google. Drives me nuts. The only way I can think of that Google is making that error is if it's reading some cookies planted on my hard drive by TOR.
The way I got around it was to reset my home page from
www.google.com to
www.google.com/ncr (which stands for No Country Redirect.) Probably won't have any effect on the problem you're having, but I thought it was an interesting phenomenon, and might possibly help others who may have the same issue but didn't know about the end-around.