I’m having a very similar issue to this since upgrading to ee2. Multiple issues, actually, but I’ll start additional threads for those. I can login via Safari on any computer, any version, but not on the newest versions of either Firefox or Chrome. Same with The Firefox Aurora build. Firefox 3 on another computer works fine, but an older Chrome build (12) is no go. The only Mac browser on which I can reliably log in is Safari.
Over on Windows, IE9 works, Safari works, but not Chrome(12) or Firefox 5.
I’m on 2.2.2. Cookies only. Switching to Cookies and session ID doesn’t improve things. I’ve tried every suggestion in every login issue thread going back a year. The same thing was happening in 2.2.1.
I’ll also mention that I’d had intermittent login issues for quite some time on ee1.6, but never to this degree. And never to these specifics. I’d guess they were almost certainly cookie issues.
OH - Forgot to mention. MSM is enabled, and I’m self-hosted.