Like the subject of this topic says. Putting the slider of the sensitivity on the lowest possible equals no sensitivity at all. It's now like 0 1 2 3 4 5 6 7 8 9 or whatever, but it's obvious to remove the first one to avoid having no sensitivity at all.
Yep if you are in a game and set the sensitivity to the very most left , you indeed can't look around anymore. Thankfully that doesn't affect the mouse speed in the menu