Several people had this problem a week or so ago, I was offering all sorts of advice because I was one of the lucky guys that it did not happen to.
Next day I copped a double whammy of login probs.
I followed your tip with the cookies but it still happened, for about 4 days.
I then reactivated my account with the info sent by email when first registering.
That, combined with your tip worked. Well for me, anyway.