No ideas here; it seems kind of random. Sometimes switching between D3D9 and D3D11 helps. But with either one, if I hit Esc while in fullscreen it gets stuck there (have to Ctrl-Alt-Del to get out).
Protip: The GSdx config GUI doesn't have an option for vsync, but if you add "vsync=1" to the ini it'll work.
Protip: The GSdx config GUI doesn't have an option for vsync, but if you add "vsync=1" to the ini it'll work.