Hm, I'm afraid this looks like a bug in ig4icd64.dll (your graphics driver):
ig4icd64!ShCompile ig4icd64!DllMain ig4icd64!DllMain ig4icd64!DllMain ig4icd64!DrvSwapBuffers OPENGL32!wglSwapBuffers GDI32!SwapBuffers QtOpenGL4!QGLContext::swapBuffers
Looks like you removed the monitor right in the middle of Mixxx issuing a command to the graphics driver. I can only guess that the driver didn't like that and crashed. :-/ can't think of anything in Mixxx that we could fix here.
Hm, I'm afraid this looks like a bug in ig4icd64.dll (your graphics driver):
ig4icd64!ShCompile DrvSwapBuffers wglSwapBuffers QGLContext: :swapBuffers
ig4icd64!DllMain
ig4icd64!DllMain
ig4icd64!DllMain
ig4icd64!
OPENGL32!
GDI32!SwapBuffers
QtOpenGL4!
Looks like you removed the monitor right in the middle of Mixxx issuing a command to the graphics driver. I can only guess that the driver didn't like that and crashed. :-/ can't think of anything in Mixxx that we could fix here.