You need to give write access to your site’s folders. You might try making empty files with those names and upload them, that way the plugin would only be writing to them.
I had the same problem, so I now use Smart Update Pinger v2.0 It replaces the built-in ping/notify functionality and (by default) only pings when publishing new posts, not when editing.
http://www.daven.se/usefulstuff/wordpress-plugins.html
I turned off its automaic feature and do my posting and then run it manually with SUPv2’s option page.
