Been happending to me for awhile also.
Thought it might of just been something wrong with my new account.
But I sign in my name changes to email@example.com (unverifyed).
Then I change it and it will change and work fine intill I sign out and back in then it changes back to that.
Its verifyed so I know thats not the problem and microsoft said to uninstall and reinstall msn tryed that with the orignal client and it does it on that also.
So it must be something wrong with there database.