Salut,

with my new (used ) T450 Thinkpad I took the step and switched to Kubuntu 16.04 LTS. Everything is fine except for one thing: frequently Plasma freezes when I click on the app launcher (lower left corner). Only plasma freezes, the computer is still running (I can switch the open apps with Alt-TAB, I can start new apps from my Konsole...).
After a reboot the machine works fine again for a while.

I've already tried to no avail:
- the often cited "Killall plasmashell && kstart plasmashell" is not working for me. Plasma comes somewhat back but remains unusable.
- moved .config and started from scratch
- I added the xenial-backports repos and got a more recent plasma (KWin 5.8.9, Qt 5.6.1) - but it's still the same.

I'm not sure, but this only happens when the machine was in "Standby" (not hibernate) for at least one time. This may also happen when a USB-Stick/SD Card is inserted...maybe this info help.

I'd like to track that down a bit cause I'm quite happy with the system as a whole and want to fix it but I need some hints where to look or which tools to use (i have been using Linux since 1992, but I'm fairly new to kubuntu). Any help is greatly appreciated.

My support-info: https://goo.gl/e8MZW5, Linux TheLight 4.13.0-37-generic #42~16.04.1-Ubuntu SMP Wed Mar 7 16:03:28 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux


Regards