Here are more details from that error:
Processing DocdirController#search (for 127.0.0.1 at 2009-06-04 11:34:39) [POST]
ActionController::InvalidAuthenticityToken (ActionController::InvalidAuthenticityToken): <internal:prelude>:8:in `synchronize' /usr/local/lib/ruby/1.9.1/webrick/httpserver.rb:111:in `service' /usr/local/lib/ruby/1.9.1/webrick/httpserver.rb:70:in `run' /usr/local/lib/ruby/1.9.1/webrick/server.rb:183:in `block in start_thread'