Cannot transfer a file/photo...

Whenever I try to send a phot in Messenger, I get a error message in the
dialog box stating the following: "This file could not be sent because the
connection is blocked. A firewall running on your computer or on the
network may be the cause. Contact your......"

I have Norton Internet Security Pro 2003 on my computer and did a Program
Scan and had NIS automatically configure MSN Messenger as well as MS
Messenger (I have XP Pro) and I do have a MS Wired Base Station MN100 with
the firewall turned on on that as well...I have been noticing on some KB's
that UPnp should be used which I don't know what that is...I do have both
the UPnP and SSDP Discovery Service disabled for security reasons within
XP's services...this was even recommended by the FBI. Is this why Messenger
cannot transfer files?

Any help with getting this function to work (send photos...video works as
well as voice but voice stinks) would be greatly appreciated.