This is the error that is causing the 503 :
2010-03-01 21:43:59.244 [INFO] [IP:50229-0#APVH_*******] connection to [/tmp/lshttpd/lsphp5.sock.344] on request #35, confirmed, 1, associated process: 29307, running: 1, error: Connection reset by peer!
2010-03-01 21:43:59.244 [NOTICE]...