I don't think it's your browser, just a feature of the site. I'm using Firefox and mine displays the same way, but only when I click back to "General Shaving Talk" at the top of the page. If you go back to the "Forum" menu and click "Safety Razors," it'll only display the 3 DE subforums.
I have the same thing in both IE9 (64-bit) and Firefox Beta (13.0), so I very much doubt it is anything with your browser. Looks like it has to due with the hierarchy of the forum and Straight Razors being a level too low so as to place it equal with the individual Safety Razor forums. I, for one, demand resolution for this outrage!