Never heard of it before. Try the official forum. Someone there might know.
https://forums.ubisoft.com/forumdisplay.php/22-Rocksmith?s=a1a9058da0611ede4685dd469b072204
Delete your D3DX9_42.dll (in the rocksmith2014 folder) and replace it with this one.
https://drive.google.com/file/d/1QhJqyhZthcTS_EyiDqJG_mmLcz1Gymcu/view?usp=sharing