Invisible banner

Few days ago something like that appear in my web browser. Its appear only on Settlers homepage and in-game (not for example here in forums or any other site). I realize that is banner or something but how to remove it? Checked PC with antivir malware and rootkit software but nothing found. I regulary clean my PC and try to keep him in good condition. Because that banner I can't acess to my friend list in game.
I'm using Win 7, 64-bit and that Firefox nightly and Ad block plus but nothing help.
Can help with that?
Thank you

I would say its some form of spyware or malware, that is your browser and/or something on your computer. Running a decent anti-malware would be a start.