@Darice - I tried that, as well as uninstalling and reinstalling the plugin... unfortunately nothing changed :-(
@Alexandru - I do not have any w3 total cache installed. I only have Akismet (which came with wordpress), and Wordpress SEO is the first plugin I am installing. So I don't think the issue relates to incompatibility with other plugins, hence why I think it is maybe an incompatibility with wordpress 3.5?