Comment 20 for bug 1492778

I had this problem using Kubuntu 16.04 and KDE 5.5.5. A workaround that worked for me was to change the compositor via System Settings, Display and Monitor, Compositor, Rendering backend, set to XRender. I can now turn the TV off and on again without it freezing KDE.

This workaround came from the following page:
https://unix.stackexchange.com/questions/219073/how-to-enable-plasma-kde-automatic-restart-upon-freeze