does the display blink before windows loads up? If so it is either a lose cable, bad vid card or bad monitor.
So check cables then it gets harder. Can you borrow another monitor to test? If so and still blinks with different monitor then you have at least narrowed it down to the system. So vid card or I guess possibly motherboard.
Now if it only blinks in once windows loads then it is possible that the drivers for the vid card are causing the problem.
Try starting windows in safe mode and see if the blinking continues.