I've noticed some apps do not track the mouse motion properly while the mouse pointer is held down. Baldur's Gate 2 (mouse movement to the right side of the screen does not trigger scrolling), Caligari gameSpace and Maxon Cinema4d demo (as well as a couple freeware 3d apps) do not track changes in mouse direction once the mouse button is held down. For example when dragging in one direction to enlarge an object, the mouse is stuck in that direction no matter which way your hand goes. (if you start by dragging right, the motion continues right regardless of whether you turn up, down, left, etc). Could be a DirectInput-related bug as these would be examples of possible programs that would use it, but it occurs on more than one mouse, I've actually tried a bunch of mice trying to find a decent one for my new imac.
