yahoo messenger problems

i m facing a new
problem in Yahoo Mes. I can not view friends webcam in my CLIENT com but I
can see them in SERVER com. When I call to their webcam i receive a message
like "Sorry, you appear to be behind a firewall and are currently unable to
use the Yahoo!Webcam servicec" IInd problem in Yahoo Mes. is It is logged
off during running time. I log many time to connet yahoo mes. So, Its
related to LAN. What should I do ? For this, If FTP server program is
required than how can I set it up. Pls help me..... & kindly tell me all
the manual/automatic setting which can solve this problem.

I m using Win XP Prof Ed in SERVER & Win 98 SE in CLIENT computers & DSL
Internet Connection 10.0.0.X & 255.255.255.0

YAHOO MESSENGER
I set up messenger in use proxies. I enabled HTTP proxy but I disable SOCKS
proxy.
Thanks