BWP works by pinging search engines when you post something new. When a spider crawls your site, the sitemap it is rebuilt, hence why I think it is much better than the standard google sitemaps plugin (less load).

It sounds like you are having dns and/or routing issues and the name lookup error is almost certainly dns related. I would try changing the nameservers your server is using (see resolv.conf) or if you don't have root access, raise a ticket with your host.