Seeing a blue box or screen in the Develop module? Lightroom CC / Lightroom 6 goes through a few checks to be sure your GPU is compatible with the new GPU acceleration. If the checks fail, Lightroom automatically disables GPU acceleration and falls back to the old mode used by Lightroom 5 and earlier. You won’t get the enhanced performance benefits, but at least the application will operate without interruption.
In spite of this, in some rare cases the checks may leave GPU acceleration enabled even though your machine isn’t compatible. When this happens, often your hardware is up to snuff, but your video driver is out of date. Some reports indicate this is more common with AMD/ATI drivers, but if you use a different card type don’t panic, the troubleshooting steps are the same.
Here’s a mock-up of what you might be seeing: