Mnementh on 21 August 2012
This is the usual browser-dialog for sites that requires authentication via HTTP-Auth (that's part of the HTTP-protocol). It doesn't come from VGChartz, as this site uses normal forms to login and authenticate. But you can include other content (like images) from different servers, the browser ask this server for the referenced data. So I think it's either an ad or an image in the thread or some signature. Probably the image was free earlier and got restricted after some time and now needs some sort of authentication to view.
