I posted about that a few days ago, been having exactly the same issue, tried different soltutions proposed here, like changing the password... I also filed a ticket, first answer was that it was because "marketplace was under maintenance and it should be working now".. didn't work. So i filed another ticket to which i was answered to clear my brower's cache and delete all cookies and if it didn't work try with another browser or from another pc!! I did.. still doesn't work. They didn't answer my last ticket.. So if anyone who had this issue found a way to fix it..
again, it works perfectly w