Well I have just gotten my monitor back after three weeks without it AGAIN. This time they picked it up as I said they had wasted enough of my time already. The kindly picked up and dropped off. Guess what... I still have exactly the same problem.
The letter that came with the repair told me that they had replaced the logic board AGAIN. This is despite the fact that the Apple care guy told me that the issue is with these 24 inch displays doing this blackout thing is with the cable and NOT the logic board. Are these guys even talking with each other? They have now replaced my logic board twice, at god knows what cost to them.
I caught a video of it this time using my iPhone (oh the irony), which you can see here. My brand new 15 inch MacBook pro plugged directly into my 24 inch Apple Cinema display - watch about ten seconds in. Its boring as ****, unless you have this issue:
http://www.mojogroup.com/AppleDisplay/Apple_24_DisplayBlackout.MOV
I pretty much give up now (it has blacked out twice more whilst I have been writing this post). Have no confidence in this product and can see why they have just mothballed them as the 27 inch displays come out. I am going to demand a refund. Being a complete sucker and hoping that the new 27 won't have these issues I will probably go for one of them.