You need to configure the firewalls to allow the communications, I found this in Yahoo Help:
"How do I configure my firewall/proxy server?
You may be experiencing an issue because you are connecting through a firewall and/or proxy server. In order to solve the issue, you will need to configure your firewall and/or proxy server. The following information should assist with your configuration:
Basic Connection:
Protocol: TCP or HTTP
Servers:
scs.msg.yahoo.com
scsa.msg.yahoo.com
scsb.msg.yahoo.com
scsc.msg.yahoo.com
Port: 20,23,25,80,119,5050,8001,8002
Webcam Connection:
Protocol: TCP
Server: webcam.yahoo.com
Port: 5100
File Transfer Connection:
Protocol: HTTP
Server: filetransfer.msg.yahoo.com
Port: 80
File Sharing Connection:
Protocol: HTTP
Port: 80
Voice Chat Connection:
Protocol: UDP or TCP
Servers:
v1.vc.scd.yahoo.com
v2.vc.scd.yahoo.com
v3.vc.scd.yahoo.com
v4.vc.scd.yahoo.com
v5.vc.scd.yahoo.com
v6.vc.scd.yahoo.com
v7.vc.scd.yahoo.com
v8.vc.scd.yahoo.com
v9.vc.scd.yahoo.com
v10.vc.scd.yahoo.com
v11.vc.scd.yahoo.com
v13.vc.sc5.yahoo.com
vc1.vip.scd.yahoo.com
Ports: 5000-5010
Firewall library provided by Distinct Corporation - http://www.distinct.com "
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If that isn't enough, try searching the help for something more specific to your problem.
Good Luck!!!
