Ja tentei varias vezes e o squid continua bloqueando o mns, estou disponibilizando o codigo do squid.conf, para alguem ajudar a descobrir este maldito erro!
P.S ele roda direitinho so que bloqueia o msn e o yahoo messenger.

##############################################
http_port 3128
cache_mem 60 MB
maximum_object_size 4096 KB
minimum_object_size 0 KB
cache_dir ufs /var/spool/squid 100 16 256
cache_access_log /var/log/squid/access.log
cache_log /var/log/squid/cache.log
cache_store_log /var/log/squid/store.log
mime_table /etc/squid/mime.conf
client_netmask 255.255.255.255
#Default:
refresh_pattern ^ftp: 1440 20% 10080
refresh_pattern ^gopher: 1440 0% 1440
refresh_pattern . 0 20% 4320
#Defaults:
acl all src 0.0.0.0/0.0.0.0
acl manager proto cache_object
acl localhost src 127.0.0.0/8

acl CADASTRO_SITES dstdomain "/etc/squid/cadastro_sites.txt"
acl SSL_ports port 443 563
acl Safe_ports port 80 21 443 563 70 210 1025-65535
acl Safe_ports port 280 # http-mgmt
acl Safe_ports port 488 # gss-http
acl Safe_ports port 591 # filemaker
acl Safe_ports port 777 # multiling http

acl diretoria src "/etc/squid/diretoria.txt"
acl cadastro src "/etc/squid/cadastro.txt"

acl CONNECT method CONNECT
http_access allow manager localhost
http_access deny manager

http_access allow !Safe_ports
http_access allow CONNECT !SSL_ports

icp_access allow all
miss_access allow all

cache_effective_user nobody
cache_effective_group nobody

http_access allow diretoria
http_access allow cadastro CADASTRO_SITES

http_access deny all
###############################################