It's ufw! After I entered "sudo ufw disable", I tried "hp-probe -bnet -mmdns" and then it worked. When I enter "sudo ufw enable" it won't work again. I also tried system-config-printer again and without ufw it works.
You should add a new exception rule to ufw so that it works like before. ** Also affects: ufw Importance: Undecided Status: New -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/764933 Title: HP network printer is not automatically detected in Ubuntu 11.04 natty (regression) -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs