Those classes on the menu are controlled by theme.skin. The only difference with preview mode is that a different cache key is used for the theme. So the problem seems to be a stubborn theme cache for the main skin which does not seem to clear as it should. Touching the theme.skin file or the web.config file should clear the cache but I have seen cases where it just seems stuck. A reboot might solve it if you are able to reboot.
What version of mojoPortal are you using?