what port is the traffic comming into? i think default msn port is 6901. if it is comming in on another port she could just be forwarding it to an open port...say 80?

She could also be running the service at home and just be calling in the info from there with her web brower or some other light weight program ( i have seen this done at high schools). i think this may be what she is doing because you say that you can only see her replies.