On one of my sites we use a php header to redirect a user to an unsecured "thank you" page after checking out. Since a recent move to a new server this redirect is now generating a very user-unfriendly warning in IE6 every time it takes place. The code is precisely the same, only the server has changed. Has anyone heard of this being a server-specific problem, or a way around it?
(It happens in IE6, by the way, but not IE7)