Shoutbox

Are you positively sure it is the same contact she talked to? it could be someone she added in her list thinking it was one of her friends.

The only thing you can really do about this is to educate your daughter to make sure she ignores this kind of thing and report it to you rapidely, as she apparently did already. It's in the very nature of internet to allow "anything" to be done so, like in the real world, there's not much you can do to prevent it (although, it is usually recommended to keep computers used by children in public places in the house, like the living room, where you can keep a watch on what's happening).

Now, to answer your original question, it is very unlikely you'll be able to get the IP address of the person she talked to. The IP address of contacts is kept "secret" by Messenger's servers for security reasons and can be obtained only when special actions like file transfers are performed.