webrick works fine but lighttpd breaks on the most simple issue

I've spent four hours trolling google search results and have scoured my own logs and can find nothing.

Until recently I used Webrick for all my http server needs. Now I'm going live to the outside world. So I download lighttpd-1.4.13.tar.gz and perform ./configure and make install. I add /usr/local/sbin (where lighttpd lives now) and I'm done. Fastcgi is built-in so I install no other stuff.

I go to the top level of my ROR app (/home/smiller/beamon-erp) and perform: script/server

Since lighttpd is on path it runs it instead of webrick. Realizing there's no lighttpd.conf in my config directly, it copies one in from /usr/local/lib/ruby/gems/1.8/gems/rails-1.1.6/configs/lighttpd.conf and then is off and running just fine.

I start my browser (firefox on RH linux) to localhost:3000 and I immediately get this error: