Mouse moves by itself

While I’m using game view cursor from GTA V (for example in Main Manu after pressing ESC) is moving slowly to the right, also while moving my mouse in game it is blocking (lagging) camera movement.
Anyone have an idea what to do?

Have you got a controller plugged in at the same time? Mine does it when I have my PS4 controller plugged in (which has a dodgy right stick). The camera starts to pan on its on sometimes.