I had the same issue an my older nvidia 550ti, and just upgraded to a gtx 950. I made it the whole first day, but now it's back.
When I crop or change the screen size it flashes a different photo for a brief moment before showing the correct photo.
Obviously disabling the gpu fixes the problem, but this isn't 2015 : )
I've had the same issue (with a different graphics card) since gpu acceleration was first added to LR.
Lightroom version: 6.7 [ 1090788 ]
Operating system: Windows 10
Application architecture: x64
System architecture: x64
Logical processor count: 8
Processor speed: 3.5 GHz
Built-in memory: 32650.7 MB
Real memory available to Lightroom: 32650.7 MB
Real memory used by Lightroom: 4277.2 MB (13.0%)
Virtual memory used by Lightroom: 5633.6 MB
Memory cache size: 4121.8 MB
Maximum thread count used by Camera Raw: 8
Camera Raw SIMD optimization: SSE2,AVX
System DPI setting: 96 DPI
Desktop composition enabled: Yes
Displays: 1) 1920x1080, 2) 1920x1080
Input types: Multitouch: No, Integrated touch: No, Integrated pen: No, External touch: No, External pen: No, Keyboard: No
Graphics Processor Info:
GeForce GTX 950/PCIe/SSE2
Check OpenGL support: Passed
Vendor: NVIDIA Corporation
Version: 3.3.0 NVIDIA 372.90
Renderer: GeForce GTX 950/PCIe/SSE2
LanguageVersion: 3.30 NVIDIA via Cg compiler
Update the GPU drive to 376.09. The one you are using has BUGs. Or turn off the GPU feature in LR.