Plasma lock screen stuck
I've just (dist-)upgraded a laptop from jessie to stretch and now there's one
problem left concerning KDE / Plasma:
After closing the lid and re-opening it, everything seems stuck, i.e. if I
enter the password nothing is shown in the password field, and if I click on
Change User, nothing happens as well. But the machine is still alive and I can
change to a text console and after restarting sddm using systemd there I can
re-login graphically again.
Any ideas what the problem might be?
Thank you, kind regards,