Comment 6 for bug 527870

I had the same problem as Renato Rosa, also on amd64. It tried first with libsdl1.2debian-pulseaudio installed, and then with -pulsaudio removed but -alsa installed. This is not through a cd upgrade though, but with the normal update manager over the internet. It turns out that the problem is caused by also having xubuntu-desktop installed (which I had installed next to ubuntu-desktop). Once I removed xubuntu-desktop (but not any of the packages it depends upon), the problem was resolved. I'll check if I can reinstall xubuntu-desktop again after the upgrade.