Rue,
Thanks for the explanation. I don't think it's the backlight then, from what you describe (hooray!). The dark blurs will move with darker areas on the screen. For example, if I move a window, the dark blur next to its title bar (usually dark blue on this machine) travels with it, like a smear of wet ink. Icons on the desktop will have smaller blurs, depending on how bright (or dark) they are. The blurs are definitely screen-content connected, so I think Bitt may be on the right track. The only other component I can think of is the cable, and swapping computers & cables should let me find out if that's the problem (I assume the cable is removable, we'll see!)

-Zeke