Why MSN Messenger ask me to verify email address all the time?

I registera MSN Messenger account using a gmail's email. When I login, MSN Messenger ask me to verify the email address else I can not modify the nick name. So, i verify and login again ... MSN Messenger still ask me to verify. It seems that my last verify doesn't take effect.

OK, let's do it again. ... After that, I login again and be asked verify AGAIN ...

I lost my endurance and I think I will crazy after one more time.