IE 7 does the same thing. A few months ago we had to set up a special 404 page for a broken link that was accidentally emailed out to hundreds of people. It was simple, the 404 page would check to see if the requested url was the bad link sent via email, if it was, it would redirect to the appropriate page. If not, we'd show a 404 page.<p>Worked great in FF but totally broke in IE7. Why? Because the 404 page size was under 1Kb, IE7 decided that our 404 page wasn't informative enough and supplied it's own.<p>The solution, as stupid as it sounds was to add enough white space to the file until it was larger than 1Kb.<p>And, you know, also stop sending broken links out.