Session gets corrupted (or lost)

Hi, I´ve made a simple site with a loguin, that in my machine works perfectly, but not on the server. The problem seems to be on the session handling. I don´t loose the SID, but the session gets corrupted. If I do a print_r($_SESSION), after the loguin i get the correct vars, but after i click on a link, while the session ID is still the same (i pass it both in the URL and using cookies) the print_r returns something like the following: __PHP_Incomplete_Class Object ( [__PHP_Incomplete_Class_Name] => user [ID] => 30 [nick] => .... This are the steps after the loguin: 1) First page that shows: http://www.site.com/index.php?b44590661eba2475ea2ff8a96d53c0b6&section=userarea print_r($_COOKIE) Array ( [PHPSESSID] => b44590661eba2475ea2ff8a96d53c0b6 ) print_r($_SESSION) Array ( [LANG] => en [user] => Username [pass] => 37bfafe651a55eef [group] => 5 ) I click on the following link: http://www.site.com/ index.php?b44590661eba2475ea2ff8a96d53c0b6&section=userarea&subsection=deletefile&id=33 2) And this page displays: http://www.site.com/index.php?b44590661eba2475ea2ff8a96d53c0b6&section=userarea&subsection=deletefile&id=33 print_r($_COOKIE) Array ( [PHPSESSID] => b44590661eba2475ea2ff8a96d53c0b6 ) print_r($_SESSION) Array ( [LANG] => en [user] => __PHP_Incomplete_Class Object ( [__PHP_Incomplete_Class_Name] => user [ID] => 30 [nick] => Username [password] => 37bfafe651a55eef [group] => 5 ) Any idea? Regards, -- Marcelo Volmaro