cookie domain: .yourdomain.com (two dots!) or yourdomain.co.uk or subdomain.domain.com or <leave it blank>
cookie path: = script path, e.g. / or /forum/
cookie name: forumname
session length: 3600 (default)
cookie secure: disabled, unless your forum runs at https://
delete your (phpBB) cookies from your harddisk before testing these settings and make sure that your browser accepts cookies from your domain, IE 6.0: Privacy settings.