Blender version: 2.74 RC
Tablet model: Wacom Intuos3 9x12
Tablet driver version: 6.3.11-4
While any of Blender's windows are active, the Intuos mouse is forced into pen mode. This happens as soon as any window is activated (but does not remain once another application is activated), making it difficult even to click on the window header as the cursor is repositioned on mouse-down.
To reproduce, open Blender and use a tablet mouse to navigate the interface. The mouse should operate as if it were the tablet's pen.