Log in status inconsistent

I love the concept of TML but I’m having trouble with different parts of the site thinking I’m logged in or not. I have the log in/out link in the nav menu and also a link elsewhere on the page to “/login/”.

The form appears fine. I log in. I go to a post on the page and it says I need to be logged in to comment. I go back to the login page and it thinks I AM logged in… sometimes. Other times I get the login form. I go back to the post page and sometimes it has caught up and knows I’m logged in and sometimes it doesn’t.

I do not have any caching plugins on the site yet.

Thoughts?