Is it possible to downgrade from 3.8.4 PL2 to 3.8.4 PL1?
 

PL2 is what introduced the login/remember me not working issues for me and with 20,000+ users it's become a customer service nightmare. I've tried all the solutions posted here, had users change their cookies, changed the cookie domain, changed the cookie prefix, and I'm still encountering some users with issues logging in. :(