Issue: Pop-Up Occuring

I'm not sure if I'm in the right place to post this, so I apologize in advance if I have. This problem has been occurring since December 2012 and lately it's been getting worse. When I'm on the main page (http://aarinfantasy.com/forum/forum.php), every time I click somewhere or leaving the site, this pops up:


No matter which I click, it does nothing. I don't know if it's spam or not... or just a bug or... if it's really a special and I'm not aware of it.