Session values are disappeared Netscape

[bhasheth]

<?php
session_start();

print $sess_name;
print $sess_prog;
print $sess_sub_prog;
print $sess_id;

print "here";
require("connect.php");
require("common.php");

if (!session_is_registered('sess_id')){
Print "Session_id is not registered...... ";
print (" <a href=\"login.htm\">Click to return back to login page.... </a></p>");
return;
}

....... more code ......
?>

When run this code from IE, it works fine and does retain the value of session variables. However, the session variable values are lost, when run from Netscape Nevigator.

Can anyone give any tips please?

Thanks.