Membership Levels Not Restricted When Using the "Next" "Back" Links in Base Temp

I am using the Twenty-Ten WP theme for this site.

I have memberships that are
--Public (Strangers allowed)
--Silver
--Gold

ETA: I almost forgot that I am using categories to limit access as this is easiest for the customer in question.

When navigating to a given post or page, any member of the public can scroll down and click to see the next post/page in a series whether it is labeled as a "gold" or "silver" only access.

I have also run into the 404 message replacing the selected permissions denied page pointed out elsewhere in the forums.

Please advise.

Thanks,

MLO