This may sound ridiculous, but I have myself on my contact list. I like to know what my name looks like.
That said, what happens is that if I colour my name, or use a custom name on my own email/contact, it changes to that name when I try to sign in.
Eg. I used the custom name "AAA" in my contact list. I close MSN and open it again. I've typed in my address, then click 'Sign In'. The e-mail changes to "AAA" which prevents me from signing in.
I'm guessing this is pointless
If it helps I'm using the latest versions of MSN and MsgPlus, but I think it happened in previous versions as well.