Horizontal scrolling doesn't work with the Microsoft Touch Mouse. This issue is present in Photoshop CS5 and the latest version of Photoshop CC on both Windows 7 and 8.1. Vertical scrolling work perfectly, but horizontal scrolling moves the canvas all the way to the right and the scrolling gets stuck. The scroll bar also breaks until you hover the mouse over it. The only way I can scroll horizontally is to hold the ctrl key and slide the scroll on the mouse vertically.