I have a site made with php which uses server side sessions throughout the site.
In fact, it\'s a site with a user login which depends on session variables and if there
IE has cookie issues with it's handling of iFrames which maybe causing the session issue you mention, take a look at these links
http://adamyoung.net/IE-Blocking-iFrame-Cookies
http://gathadams.com/2007/06/25/how-to-set-third-party-cookies-with-iframe-facebook-applications/
http://nileshtrivedi.in/blog/2008/09/01/iframe-cookies-and-internet-explorer/