I just did a dist-upgrade and had to reboot my MD (I'm currently on 1004) and it boots into KDE immediatly. I tried the activate Orbiter, but that didn't work. So I searched to forum and found this for the same issue under 8.10
sudo update-rc.d -f kdm remove
but that didn't work either. So I tried to rebuild the image, but after trying the update again...it booted only into KDE again.
So right now I deleted the MD and created a new one, but so far will stay away from the update.