Shoutbox

Okay this has nothing to do with Plus, but I dunno where else to go and this problem is annoying. A friend added me to their msn list, but I was online on both my phone and my computer. I didn't receive the invite on my computer so I accepted it on my phone. I can talk to her via my phone but we can't communicate from my computer. It won't let me. Says she doesn't have messenger, even though we're already talking. I double checked the spelling, I tried having her delete and re-add...nothing's working and I'm getting really sick and tired of it. Please help.