I was just wondering...

i used languard to scan my home network and I found the router of course, our hp printer and my laptop. However I know my girlfriend is online and I know the last octet of her ip. So why can't I see her? And how can I make it so I can't see myself? I'm using Kerio's Personal Firewall. We both are running XP. If I can't see her because of something simple, is there another way to find her? I can't ping her either so I'm guessing she is blocking/dropping icmp packets right?

Thanks guys.