Recently i've upgraded to plasma 5.2 and qt 5.4.
My sandybridge notebook with hd intel have a fullhd monitor connected with
HDMI.
Startup takes a while and when the desktop appears I found drkonqui windows of
plasmashell and Krunner tell me they have crashed. This appens only on startup
because plasmashell restarts automatically with no issue and I was able to use
krunner.
The crash happens also if the external monitor was hot plugged or unplugged, in
this scenario kwin crashes too.
The crash is reproducible always and is related to Qt5 QScreen::handle() and
libqxcb.so.

Krunner and plasmashell will not crash if only the laptop monitor is used.