Error Code: 8007007f Why I Can't Sign In To Msn 9.0 ?

Why i can't sign in to msn 9.0 ? - error code: 8007007f

I have the latest version of Windows Live Messenger ..
But if I go, I can not!
said that the entry point LEARNED ................................
Error Code: 8007007f
someone please help me!
thx ..