GPU rendering - renders only world color

I’m having a problem with Cycles and OpenCL rendering.

Whenever I render with the GPU, the world color gets in the way and I can’t see anything else.


CPU rendering works fine:
GPU rendering doesn’t:
However, GPU Rendered View does:


Windows 10 Pro 64 bit
AMD Radeon R9 270X (driver
Blender 2.77 Steam version

Everything was working fine yesterday, then Blender got entirely black (the entire window), then the render doesn’t work anymore.

It’s the driver. Reverting back to the Windows default driver (15.11) solved it.
I’ll test 16.3 to see if it works.

I just don’t understand how the driver worked for several days without problems.