Boost: Session is active, yet gets cached pages

[demon326]

I don't know if this a nginx problem, or a drupal side problem, but i'm using this module with nginx and it works, but my users are getting logged out on the website, or are logged in, but only after going to /user/login.

I do notice a pattern:
Uncached page: Anonymous users hits page, cached version gets created and proceeds to logon.

Cached pages: The user access the cached pages and it looks like he is logged out, but in reality he's still logged in.(session cookie still in the headers), yet the page shows the login form and no adminmenu on top.

Only pages NOT hit by a Anonymous users are normal, once the Anonymous has hit the page, the logged in user shows logged out.

Header cached page:

Header Logged in page:

Dont know where to search for the fault...