[PHP-WIN] why seesions always lost

[yuegong]

Hi ;
    I set a intranet App by PHP and Mysql; when i test on my NootBook it is ok . but 
when i move it into the network , the seesions always lost, then users must relogon, 
it is carking.
can anybody tell me why? I have set the session.cookie_lifetime   = 0.
    Thanks