You are behind a router/firewall, it is the device seen by the internet,
while your PC is assigned a private IP by the router. The ip assigned to
the router most likely changes periodically (especially when you turn it
off and on again). Going into the router's setup will show the current IP,
but there's an easier way:
To find out what it is RIGHT NOW, simply type this into your browser:
the IP reported there will be good for your current session.
if you use netmeeting a lot then make this a bookmark/favorite in you
[I'm suprised your consultant didn't know this URL; tell him about it.
hopefully he will know how to guide you to open your firewall to allow
netmeeting to work! UPnP can do that automaticlly tho, and I'll bet it
isn't disabled on your machine. Perhaps a visit to www.grc.com is in