I have the following problem. I noticed that my HD 4000 isn't being used when i open the game Chivalry: Medival Warfare. As the result of this the game is uplayable (1-2 fps at lowest settings and lowest resolution). Otherwise everything runs normal and the GPU is properly used (youtube, movies and other media, though i haven't tested any other games) but in Chivalry the GPU load stays at 0% or really at minimum.
I have the latest drivers and ht HD 4000 is running in my ASUS Zenbook UX31A with an i5 3317u 1,7 GHz.
I find my problem very odd, since i saw that a lot of people on youtube or forums have no major problems with Chivalry (and other games) on the HD 4000.