please send a link where i can see the problem and a copy of the page in a zip archive to troubleshoot.
also, double check that the server is properly configured to save session variables by using the session test page in this thread:
showpost.php?p=23826&postcount=2
if the session test fails it is likely a problem in the php.ini file with a bad setting for the session.save_path, you will need to contact the host to have the issue corrected.