Certain regions of the Firefox window are translucent allowing the desktop image to show through. These regions are everything but the large central internet site image region which behaves normally. Unless the desktop is completely black this problem makes reading the tabs, address bar, and the bookmark are difficult to impossible. I experience this problem only on my new Dell U3011 monitor. Firefox is the only application that exhibits this problem on the Dell monitor. The monitor built into the laptop that drives the Dell monitor does not exhibit this problem. The laptop is a Lenovo W540 running Windows 7 64-bit. Thank you very much for your help. Steve Schupbach