When I use my "Put Display to Sleep" hot corner my display blackens with no desktop image visible behind the black, as opposed to grelber's description of what he is seeing:
Actually, the screen doesn't go "black", just extremely dark, but one can see what is there very dimly.
Since that's precisely what I see when I turn my screen brightness down to -0-, I suggested a possible hardware issue, but grelber is disinclined to run Apple Hardware Test (again, not that I've got the least idea whether it will find anything).
