My wife just asked me to check out a link on her site because it was giving her a 403 error.
The message was You don't have permission to access /wp-content/cache/supercache/essenciafeminina.blog.br/medicos//index.html.gz on this server.
It only happens to people who are not logged in because of how the .htaccess file is set up by the plugin. I logged into the server and saw that all of the files in that directory had permissions 600 (read/write for owner, no permissions for group and others).
I chmod'ed the files so that all could read and the problem stopped. There seems to be a problem when creating the files in the first place.
Cheers,
