I installed Plasma 5 on a brand new laptop Acer E5-573G .
Every time Plasma started the would appear 1 or 2 messages indicating Plasma had crashed with Segmentation Fault 11 in PIDxxxx. There were no other symptoms and KDE / Plasma performed normally after that. The appearance of the messages was merely annoying, they also occurred when logging out.
I accidentally found something about it with new Intel chips here https://mail.kde.org/pipermail/kde-distro-packagers/2015-August/000088.html applied the fix and the error dialogues stopped appearing.
However, they sometimes do still occur on selecting “leave”.
I was wondering if anyone else was having this problem. It has appeared on 2 machines I have with i7 processors running Plasma 5.4 and earlier versions of 5.