User-Agent:       Mozilla/5.0 (X11; Linux x86_64; rv:48.0) Gecko/20100101
Firefox/48.0
Build Identifier: 

Hello,

Since a few weeks (3, I think), KDE has not been able to launch applications
except for the applications already launched at start up (Firefox, Skype). I
have tried on X and Wayland with no success.

After a while, the screen freezes and I have to shut the computer down.

Reproducible: Always

Steps to Reproduce:
1. Click on application icon or search application (alt F2)
2. Nothing happens

Actual Results:  
Application doesn't launch. I have tried to launch a Konsole to see if I could
get some error messages but I couldn't.


Computer information: nVidia graphic card (Quadro 400M)