It happens to me as well (display: Samsung 37in Full HD LCD - 1920 x
1080)
All the windows wider than something about 1024 pixels look black, they
display correctly if resized smaller (like half of screen width).
--
background image and full screen video is not displayed when screen size it set
** Description changed:
my screen is set to 1440x900 and i don't have any background image. my
background is a black screen. if i try to watch video at full screen at
this screen resolution all i get is a black screen. if i set the screen
any higher at 1680x1050, firefox at full screen
