To be honest, I want to lay the blame on the virtual machine graphics interface, because it's breaking only when mipmapping is enabled, and I've never experienced this glitch before on any of AMD, Nvidia, or Intel graphics before. However, I can't find anything about this problem online.
When I zoom in really far on your screenshots, I can see that one of the two layers has half the resolution of the previous one, which indicates that they're two levels of detail of the mipmap. The reason one fades in and out is because as you zoom, it blends gently between different resolutions of the image. That's why the transparency levels change when the zoom levels change: the closer one of the mipmaps gets to native resolution, the more it's weighted. Normally this is completely unnoticeable, but in this case there's an offset between the two levels of detail, and we get the above result.
I'm not sure there's anything I can do, except say to turn mipmapping off (which you say eliminates the problem). Personally, I leave mipmapping off anyway because it adds a tiny bit of time to the processing, and I like the sharper image when not mipmapped.
As for checking whether the driver is actually the issue, though, can you try running a 3d application (game, maybe) and see if things like textures are screwed up? It seems like OpenGL 3.0+ (which you have) has automatic mipmap generation, so if that's the problem then it'll show up in other situations.