При добавление произвольных символов типа ^%&@# в куку сессии мы получаем:
Warning: session_start() [function.session-start]: The session id contains illegal characters, valid characters are a-z, A-Z, 0-9 and '-,' in /home/morga145/domains/wmpost.info/public_html/includes/system.php on line 3

Warning: session_start() [function.session-start]: Cannot send session cookie - headers already sent by (output started at /home/morga145/domains/wmpost.info/public_html/includes/system.php:3) in /home/morga145/domains/wmpost.info/public_html/includes/system.php on line 3

Warning: session_start() [function.session-start]: Cannot send session cache limiter - headers already sent (output started at /home/morga145/domains/wmpost.info/public_html/includes/system.php:3) in /home/morga145/domains/wmpost.info/public_html/includes/system.php on line 3