Well,

I have seen many reports about this.

I hope the fix to this. 

When I do session_unregister and session_destroy nothing happens.
The file is there with the information of the variables registered.

Code:

First script :
-------------------------
session_start();
$sesname = "name" ;
session_register("sesname");
-------------------------

Second script:
-------------------------
session_start();
if ($exit ) {
    session_unregister("sesname");
    session_destroy();
}
--------------------------


configure php...
'./configure' '--with-apache=/opt/apache_1.3.12' '--enable-versioning' '--without-mysql'
'--with-sybase=/usr/local/freetds' '--without-gd' '--enable-track-vars'
--with-system-regex' '--enable-trans-id'

session.save_handler = files
session.save_path = /tmp                                                                      
session.serialize_handler = php
session.use_cookies = Off