Hello! I've seen several support questions about this problem. When a new FF window is opened, there is a white bar blocking the top of the window, from the top of the screen down to approximately the bottom of the address bar. Alas, none of the answers have quite worked for me. Though often simply described as "white" in other help requests, what I have is an area that while visibly opaque (white), is transparent to the cursor. If another FF window is still open behind it, clicking anywhere in this bar will switch to that window and act there. If no other windows are open, clicking there will open links on the desktop. Some help requests have suggested checking for full-screen mode. Pressing F11 to enter full-screen, then F11 to exit full-screen, does fix the problem within a single window, but the problem persists with other new windows, or if the program is closed and reopened. Other help requests have recommended restarting in safe mode. Doing so actually gave me an initial FF window with the white bar, though oddly only covering the left third of the top of the screen. Given the problem appeared immediately in safe mode, I suspect it's not an addon. Starting again out of safe mode does not change anything. I have not yet tried the reset/refresh FF option; that, I suppose, is next, but I'm hoping to hear if there are other suggestions. Thanks!