Having the same problem Jak had “I replaced the old sunrise.php and domain_mapping.php – now all that shows up is a blank page” This is a new install. If I delete domain_mapping.php the admin site seems to work fine, but when I try to log into any blog other than my primary when I put in admin and my password, it just keeps coming back to the login in screen with no errors. I’m pretty new and clueless at this, so thanks for any help.