It poorly seems that my 23" apple cinema display adc is suffering from some similar symptoms shown above since few weeks. The Mac mini even stopped to sing is trumpet sound when starting up.
The first time I used the screen, everything was nice, clean & bright with normal behaviour sleep mode. Wow! but not for a long time... From about day 3, following an update (itunes and security pack and quick time, i think, can't remember) it could not wakes from a sleep state, screen staying black and the power light lighting in a repetitive motion (short-short---long---;etc.). Emergency solution then was to unplug/plug again the power cable of the dvi-to-adc adapter to wake the screen back. The repetitive and intermitent syndroma continued untill that day, 2 exact weeks after I bought the apple display from a particular, there it showed no signs of life. The Mac Mini starts (but no trumpet sound), drive sound as normal but no power in the screen, the abnormally cold adc/dvi brick is making a high pitched quiet noise with some clicks in a uncoordinate motion.
I tried all possible tests, plugging the display to a powermac g4 with adc/vga video card = still no power to the screen/ then check the mini with other DVI screen = video card of the mac is working great. I'd just returned the adc/dvi adapter to the retailer for an exange, waiting to see if a new adapter could be a possible solution. But the test with the powermac tells by itself, the bug is in the screen (but where in that d%?$ screen?).
Some of you talked about a upgrade or firmware case; considering the long period of time those toubles occurs to so many users joined to the important number of similar cases in this topic column, I can't figure out how apple can endure that recurent problem unresolved with only vague firmware issues or explanations in counterparts. any other similar cases, or issues?