Does it perform better at lower than 1280 x 960? I have seen where some monitors will act this way when set to the max and they struggle, going down 1 resolution size can sometimes fix this.
I have an old Dell monitor that is acting like this and going back 1 resolution setting fixed it. When setting it to the max that it will display before black screen no sync it will do just like your problem. But going lower 1 more from the max that it will display at fixed the issue of having to use the windows key and flicker between picture and black screen.