iptables and named shutdown

[decola]

Hi all!
Below my iptables script:

#!/bin/bash

/sbin/iptables -F INPUT
/sbin/iptables -F OUTPUT
/sbin/iptables -F FORWARD

/sbin/iptables -P INPUT DROP
/sbin/iptables -P OUTPUT DROP
/sbin/iptables -P FORWARD DROP

/sbin/iptables -A INPUT -i eth0 -m state --state ESTABLISHED,RELATED -j ACCEPT

# to avoid ping flood
/sbin/iptables -A INPUT -p icmp --icmp-type echo-request -m limit --limit 1/s -j ACCEPT
/sbin/iptables -A INPUT -p icmp --icmp-type echo-request -j DROP

/sbin/iptables -A INPUT -p tcp --dport 22 -j ACCEPT
/sbin/iptables -A INPUT -p tcp --dport 80 -j ACCEPT
/sbin/iptables -A INPUT -p tcp --dport 53 -j ACCEPT
/sbin/iptables -A INPUT -p udp --dport 53 -j ACCEPT

/sbin/iptables -A OUTPUT -p tcp --sport 22 -j ACCEPT
/sbin/iptables -A OUTPUT -p tcp --sport 80 -j ACCEPT
/sbin/iptables -A OUTPUT -p tcp --sport 53 -j ACCEPT
/sbin/iptables -A OUTPUT -p udp --sport 53 -j ACCEPT
/sbin/iptables -A OUTPUT -p icmp -j ACCEPT

/sbin/iptables -A INPUT -s 127.0.0.1 -j ACCEPT

Every service works correctly but if I try to shutdown named the system freezes, no further prompt is being shown.
What's the error?