hi there.
welcome to the forums,if you can sign in with both yours and your daughters but not you partners then it appears it is a problem with her login details,it is so easy to get a single letter or underscore etc etc wrong when entering details when you first set up things and if you have told msn to remember me then it will obviously remember it,check all details etc with the old laptop to make sure it is correct,again if she can sign in on the old laptop then her account is obviously ok,also do you get an error message at all ?? if yes then feel free to post the error message back here so we can see what is going on,but it sounds like a msitake on entering her details.let us know how you get on.