hi, u cannot store any resource variable (e.g. a db identifier) in a session... from php.net:
Note: It is not currently possible to register resource variables in a session. For example, you can not create a connection to a database and store the connection id as a session variable and expect the connection to still be valid the next time the session is restored.
however, maybe u wanna use persistent db connections - check out www.php.net/mysql_pconnect for further information.
hth
