I was using Firefox 3.6 , and am using Windows Vista 64 bit with Flash 10.0.22.87. Every time a window (File explorer , some media player or another application) appears on top of Firefox 3.6 window and if I am dragging this other window (file explorer or some another application) with the mouse around the Firefox browser window, the input focus will be lost to the Firefox window. So if I drag a window explorer window and move it around in front of the Firefox window, Firefox steals the input focus and the mouse will be pointing at the browser instead. This happens all the time. I tested my trackball and is functional. I have no problems with other application on top of others and dragging it as described above. I downgraded Firefox to 3.5.1 and the problem is gone. == This happened == Every time Firefox opened == another windows is on top of Firefox window