Session userdata disappearing after session updates

[eluser]Unknown[/eluser]
Hi,

My session user data seems to be disappearing every time the session refreshes. My application has a login page that sets an is_logged_in variable in the session. All pages (and ajax pages) verify that the user is logged or redirects to the main page. When the session refreshes the is_logged_in variable is lost. Why is this? Note that the session is not expired, just refreshing.

Just in case it matter, this is occurring in safari.

thanks,
Jeff