2
'session_start' is a built-in php function. I'm not sure what that error means, perhaps your server configuration has a slight problem. Check these docs for some help (I just did a google search for your error message):
http://p2p.wrox.com/archive/pro_php/2001-08/37.asp
http://www.faqts.com/knowledge_base/view.phtml/aid/13108
good luck!