Plugin installs OK, but links are 403

I believe I've installed s2Member plugin correctly. Even tried it on two different sites (both are hosted at WebHero.com)
However, when I choose the s2Member dropdown in the dashboard, any link I click, such as "General Options" brings me to a "Sorry - Error 403 | This Page is Forbidden " page. Any ideas on what I'm doing incorrectly?
However, when I choose the s2Member dropdown in the dashboard, any link I click, such as "General Options" brings me to a "Sorry - Error 403 | This Page is Forbidden " page. Any ideas on what I'm doing incorrectly?