Let me clarify the "new user" test results. Dolphin was working normally in new user, as well as apps that bring up "Run as root - KDE su", like synaptic or Konqueror in super user mode. When I logged out and logged into my "old" user, "Run as root - KDE su" would no longer come up when starting synaptic or Konqueror SU mode. That's what suggests that interprocess communication (namely 4.5.0's interaction with dbus) is not right in 4.5.0. Eventually this is going to break something important.