I finally got in by deleting wordpress automatic upgrade plugin. I thought I had tried that earlier. I don’t know why it would suddenly be causing a problem.
There is a new thread: http://wordpress.org/support/topic/201746?replies=8
Seems there are several of us today, with the same problem.
PS I am hosted by bluehost. Only one out of four blogs has the problem. It is in the root directory.
I am having the same problem. I’ve been through all the old posts and tried everything. I use FF3 and IE7 on two different computers, with 2 different versions of Windows. Nothing works. I just get returned to the login page without errors.
