Created attachment 690591 [details]
This screenshot shows how it ends up finally, get stuck here, this is it.

Did a clean install of 42.2b1, with KDE.
The PC is of 2007, with some Nvidia Quadro graphics card of that time.

The installation seemed to work finally, but on first boot, what happens is:
The first coloured pictures of Grub and of the animated background work. But
when it is then fully up, the task bar is visible for less than a fraction of a
second, it immediately vanishes, no more windows are visible, just the
background remains visible and the mouse arrow.

Please see the screenshot, to get an idea.

I can do nothing from there, except moving the mouse. But whereever I would try
to click on, e.g. the corner, nothing happens anymore. 
So when I reach that state "fully booted up", this KDE system is unusable to
me.

Not sure which component to open this ticket against, and sorry I might be
wrong here:
- it might be a KDE issue
- it might be a graphics card issue (but in this case, why do I still see the
background screen, and the coloured screens before)
- or it might be an installation issue in the sense that I should have chosen
to go with non-default screen resolutions or drivers, but wouldn't know which
to select in that case.

As I couldn't open any window after this boot, also not sure how to debug this
further.