Firefox 4 - 6 does not display on my machine. I am running W7 Pro, 64 bit. The window blinks at random places. When touched with the pointer, items go completely black. Scrolling cause the entire window to go to black and can only be recovered by moving the pointer across the window. The address bar cannot be seen if touched by the pointer and on and on. . . I have un- and reinstalled the browser with and without a reboot. Tried a clean install after a registry clean and defrag, still the same. It works (4) great on all the other machines running XP and Vista.