session_destroy() fails...

I am looking into sessions at the moment and havn´t got it all working properly to continue my journey. I´m having problem with the session_destroy(), and after some searching in the archive, I found out that other people have had this problem aswell, but I didn´t find a fix... Here is the error message I get: Warning: Session object destruction failed in E:\Inetpub\wwwroot\testscript\sessions\test.php on line 5 Here is my code: <?php session_start(); session_register("value"); session_unregister("value"); session_destroy(); ?> Is this error caused by php.ini, my webserver or other? My configuration: IIS 5 for Win2k PHP 4.0.3 PL 1 Thanks // Tobbe