Try to deactivate the GPU support -> Adobe Lightroom GPU Troubleshooting and FAQ
Take a look especially on Solution 2 -> Manually deactivation.
Have you install the latest version of Lightroom 6, its version 6.14
Thanks Axel. I've done that before and it helped for a while only. Also, when I now open that file in the text editor, there is only one mention of 'autoBahn' and that's not the one they are talking about in the solution given since there is no mention of ' = true' (or false) of it.
I have installed the latest version yes, I used a link that I was directed to by customer support themselves.
Please enter the line useAutobahn=false manually in the file com.adobe.Lightroom6.plist.
That worked, thanks a lot!
The only thing is, this will happen again and again, just a matter of time before either one of the two problems arises again