Comment 32 for bug 670788

@Daniel - done so:

I can confirm that:

sudo apt-get install ppa-purge (if you didn't already have it installed)
sudo ppa-purge ppa:kubuntu-ppa/ppa
sudo aptitude install kubuntu-desktop
sudo rm -rf /tmp/kde*
sudo rm -rf /var/tmp/kdecache*

results in a working KDE 4.5.1.