The problem is really in favicon (Win7, FF4) - error pops up even if no favicon is set in document header. Once line <link rel="shortcut icon" href="favicon.ico" /> added AND .ico file is valid (16x16px) AND in correct place - error disappears. Another thing, you have to make sure that the line <link rel="shortcut icon" ... > is not added twice to your page. Just right click and view page source t