Are you saying this is happening in *every* browser when run under 2K or NT, and for *every* geeklog theme? If not, please be more specific. A screenshot would also be helpful to show people what exactly you're refering to.
Also, the fact that it only happens for PHP pages is kinda strange. As PHP runs on the server-side, the browser has no way of really knowing whether a page is PHP-generated or not.