Well, 3.7.1 did it's auto update for me...

FAIL.

A site that was working perfectly prior to the update now issues the "Error: Cookies are disabled or blocked..." message whenever *anyone* tries to log on. nothing on the site was changed other than the WP 3.7.1 update; There are already a few threads on the Wordpress support site relating to this problem, but the standard answers are all that are being given: Disable your plugins, clear your cache, delete your cookies...

Well, I've disabled all plugins and switched to a stock twenty twelve theme to no avail. This issue is cross-browser. I've cleared cache & cookies on each browser I've tried (IE, Firefox, Chrome, Safari...)

Apparently as part of the new update login.php is now issuing a test cookie that is not being properly read on the first pass. If you re-enter the username and pw on the error screen, you will be successfully logged in, but far to many users are not giving it a second try...

So, basically, this nifty new update has tanked my - and a great many other users - ability to have people log on to their WordPress sites.

Any ideas how to fix this?