Not quite sure what you're going for here... but I'm going to take a shot.

Visitors without user accounts are part of the Group "Guest" - make sure you prevent access to that group by unchecking "Read"

If you're logged in (as an account that should not see the page) you may be a member of another group that does have access - recheck your permissions. By default all user accounts belong to "Registered Members"

Finally, the "Super User" sees everything - so if you're logged in with the admin account it ignores permission settings.

Thanks Glockops, I think my initial plan was over complicated and the problem was mainly due to the auto nav and the fact that all registered members have the same permissions as a guest plus extras. So for example I couldn't have a visitors page that would only be visible to guests as this would also include guests + registered members.

I have managed to work around it now by having a link on my visitors page which enables members to see their profile.

Thanks for taking the time to help out :)