I was stupidly playing with hdparm features, and after experimenting a few non recommended parameters, I nearly destroyed my / partition (the system one). So my Kubuntu was unusable on my laptop.
Seeing the few problems (bugs) I have encountered using Kubuntu, I decided to switch to Ubuntu and install the KDE desktop (not yet done, I am still under Gnome). I will have more or less the same as Kubuntu. However, the administration tools will be the one from Ubuntu, which, in my opinion, are a bit better and especially more stable.
Speaking of stability, I decided to move right away to Ubuntu Dapper Flight 5, so still a release which is under development. So, I do not expect it to be pretty stable. But I am planning to play around a bit with my laptop, so this release was suiting my idea then.
Nevertheless, as Kubuntu and Ubuntu are pretty similar, I will keep to the category Kubuntu for both distributions.