I had the same problem, and Terminal said that:
"Last login: Sun Sep 26 18:46:54 on console
macbook-de-rogerio-z-215:~ rogerioz$ cat /var/log/system.log | grep 'proxy\[[0-9]*\]'
Aug 17 00:00:09 macbook-de-rogerio-z-215 proxy[506]: Wrong AV checkurl response code (555)!
Aug 17 00:00:09 macbook-de-rogerio-z-215 proxy[506]: Wrong AV checkurl response code (555)!
Aug 17 00:00:10 macbook-de-rogerio-z-215 proxy[506]: Unexpected AV response code (555)!
Aug 17 00:00:16 macbook-de-rogerio-z-215 proxy[506]: Wrong AV daemon statistics pop response code (555)!
macbook-de-rogerio-z-215:~ rogerioz$ "
Ad it all repeated a zilion times...