Note that the use of content advisor doesn't actually "block" the site - it still renders (invisible window), and CA checks the content to see if it is allowed or not. So, if you're blocking sites due to malware/virus concerns, this is *not* a good way to do it. At that point, using a hosts file will work, but it may be better to use a
proxy autoconfig script. The script itself isn't the easiest to create, but you can whitelist some sites (or domains), and block everything else (whereas a host file is more of a blacklist, and needs to be continuously updated).