Created attachment 860529 [details]
dmesg with drm-intel kernel
The drm-intel kernel showed exactly the same issues with black screen flicker
after boot. But now - after some runtime - the screen is stable. Only the mouse
freezes for a moment each time it comes close to menus or dialog boxes (or
other stuff that reacts on mouse).
I see this behavior for the first time, but the other kernels never ran so
long.