Perhaps this link could help you :
http://www.phpdig.net/forum/showthread.php?p=9414
If you modify php.ini, perhaps you have to restart the machine before it works.
Could be there are several php.ini files.
What is your configuration (windows / linux, etc...) ?
What are you trying to spider (localhost or external) ?
Did spider.php create anything in the sites table or not ?