Can not send file or share app. by messenger

Greetings,

I upgrade my comp from 98 to XP Pro and I realised that
Win. Messenger can not send file but I can receive. I m
connecting inter net by Cable and using router to share
w/ another comp. I have disabled the firewall of router
and it is written on the help files of Messenger
that "Both incoming and outgoing TCP connections use this
range of ports: 6891 to 6900. This allows up to 10
simultaneous file transfers per sender. If you open only
Port 6891, users will be able to do only one file
transfer at a time." I open only port 6891 from my
routers settings but still I cant send any file but I can
receive. Is there any way to open the port other than
settings of router? I dont know how to do that can you
help me please?

Thank You sooo Much.
Sentiere.