Does it work with a different computer attached? I'd try to whittle down the symptoms so that you can determine if it's the fault of the video card (hardware or settings) or the monitor itself.
I have a Samsung 710V monitor, which will not start - I just get a black screen when I switch on.
It is connected to a Dell laptop (Windows XP) and worked fine until recently when it was disconnected from the laptop and then re-connected. I have checked that all the connections are ok. Now the green light for the on/off switch in the middle flashes all the time, but the screen remains black.
I would be grateful for advice on how to fix this.