Dbus not working as expected on MacOSX

[mkae]

I've got a question concerning dbus.

I installed kde 4.7.0 via MacPorts on MacOSX and experience an annoying problem with dbus since many weeks which is preventing starting of any KDE application [1].

Only today I found the tool qdbus which revealed that it is impossible connect to the system dbus:
@$ qdbus --system
Could not connect to D-Bus server: org.freedesktop.DBus.Error.NoServer: Failed to connect to socket /opt/macports-test/var/run/dbus/system_bus_socket: Connection refused@

Checking the socket shows that it should be read- and writeable to anyone:
@$ ls -la /opt/macports-test/var/run/dbus/system_bus_socket
srwxrwxrwx 1 root messagebus 0 Aug 7 10:18 /opt/macports-test/var/run/dbus/system_bus_socket@

One can also see that the path towards the socket is free:
@markos-imac:~ marko$ ls -la /opt/macports-test/var/run | grep dbus
drwxr-xr-x 4 messagebus messagebus 136 Aug 7 10:18 dbus

markos-imac:~ marko$ ls -la /opt/macports-test/var/run/dbus
total 0
drwxr-xr-x 4 messagebus messagebus 136 Aug 7 10:18 .
drwxr-xr-x 5 root admin 170 Jul 22 16:51 ..
-rw-r--r-- 1 root admin 0 Jul 22 16:51 .turd_dbus
srwxrwxrwx 1 root messagebus 0 Aug 7 10:18 system_bus_socket@

In the last lines I see that there is a mix of messagebus and root in ownership… But I guess this isn't the reason.

Any ideas what could go wrong here?

Greets,
Marko