Hey mate,
Just to let you know, I am experiencing the exact same thing as you are. This in itself is interesting, as I thought it may be my machine that was being weird, but if you see a couple threads below this one I posted something with the same issue... (
see here)
I am currently using a different chat client, because I refuse to use MSN without Plus! I don't think you'll be able to fix it - there's some weird conflict going on somewhere, and especially seeing as it's not an isolated issue. This is probably of no help to you, but you're not experiencing a problem that no one else is!
Let's wait and see what happens!
Dave