Vortex Wars

Many times when I try to log in (auto login) it gives me an error message: You can run only one instance of this game on your computer. But I don't run this game anywhere else on my computer. When I hit the login button it says: Your account has been used on different computer, you have been signed out. But I didn't login anywhere else. I have to close IE completely before I can login again. Pretty irritating when I allways have 2-4 webpages open.

EDIT: I also have to close all other IE tabs and also all windows.

EDIT2: Only happens the second time I open the game, even if I log out normally! I did refresh IE but now I still can't login.