gnome-nettool hangs when hostname resolution fails

My internet connection is broken once in a while, and i just had the
gnome-nettool program hanging.
I'm behind NAT, and my software router was rejecting my packages ("sendmsg:
Operation not permitted" if i pinged from there), because the iptables were not
set up correctly.

That resulted in problems when I was trying to ping a hostname with gnome-nettool:

1) make sure the dns is broken in the right way*
2) Open the 'ping' tab
3) fill in a hostname, e.g. www.aap.nl
4) hit ping
5) problem.

* The right way is to make your router's iptables rules drop the packages. (I
fixed it by running 'ipmasq' on my router). Moving /etc/resolv.conf out of the
way does not seem te reproduce this problem, as the dns resolution problem is
then detected immediately (When resolv.conf is missing, normal 'ping' also
immediately returns with 'ping: unknown host aap.nl'; things fail smoothly)