Thanks that's fixed it.
My graphics card is a AMD 7950 and running drivers 15.20 Looks like it's this issue - Adobe Photoshop Lightroom Help | Issues with Lightroom CC/Lightroom 6 and AMD graphics cards | Win
I am having similar issues with my current setup.
I can't uncheck the box though as it hangs everytime I try.
Radeon R9 270x series Driver version 15.200.1046.0
I may have to uninstall the driver
You are a superstar !!!
Thank you, that worked for me !!
I assume they are still working to fix it?