Not able to view site with Membership

I have 3 levels set up for Membership. Visitor (unregistered strangers), Subscribers (people that have registered), and Members (people that have bought membership).

I have 2 subscriptions, a 6 month and a 1 year. Paypal gateway.

I also have Marketpress installed to sell items.

I want visitors to see the store and pages.

Subscribers to be able to comment.

Members to see posts and content in the posts.

I set up access levels for each group.

BUT even when I the administrator go the site I can’t access anything. I get the front page only. I click on something I get an error page.

What have I got wrong?