i think it is a problem with the messanger itself!!
Try to logon from other computer..it must work.
i think you need to re-insatll the messanger..
Cheers
Mansour
go to control panel then go to windows live esstail then click reapir if thats not there click unistall and u should get option to reapair it it will then try to reapair msn then restart your computer after that should work again if no post back