Selecting ShowDepth just shows a black screen, and most other Compositors you can select don't work correctly at all. I guess that is since they are all based on depth somehow. Only happens with OpenGL.
So maybe only the Depth Buffer is broken here.
I set this as major as it may hint to a more general problem. Maybe it is not, though
Windows 7 64-bit, GeForce 580 GTX, Compiled with MinGW GCC 4.7.1