ATI released new drivers yesterday! And there it states that "Starting X on a DVI display no longer results in noisy or flickering output with some displays". Did you check it out Flavio ? I must do it but I don't have time to do it now :(
Unfortunately, that also didn't work... The same stuff - black screen. So I'm waiting for the 8.12 series, just as Matthew wrote. But when will it be ;)