Session Variables

I searched the site first to find an answer to this question but had no luck...I apologize if it is redundant.

I am curious how I can change the session variables so that users on the Windows platform (IE 5-6 specifically) are logged out when they close their browser window or quit their browser. Right now I have no problems with this process with Safari, Camino, Opera, or IE 5 on the Mac.

Is this simply a problem with IE 5-6 and how it handles Geeklog's session variables? By changing the lib-sessions.php file will I be able to make these changes. Forgive my naivety concerning this subject but I am an aspiring intermediate PHP/Geeklog administrator ;)

Thanks in advance for any help and insight the Geeklog community might be able to offer.

Chaseter