I have Ubuntu 12.04 LTS and I installed the KDE desktop via the
sudo apt-get install kde-plasma-desktop command (I wanted less stuff than the
sudo apt-get install kubuntu-desktop command would install).
I did a bit of tweaking (changing the order of the buttons/messing with decorations & themes, nothing terribly internal). For some reason, KDE will randomly lock the screen. Is this a problem with Ubuntu, KDE, a KDE theme, or what?
This isn't a gargantuan problem as I prefer LXDE and will be using it (it runs fine the way I want it), so if you're working on and about to find the cure for cancer, don't drop that to help me.