I recently picked up a 22 inch Samsung LCD monitor, it was used but it worked perfectly when I got it. Now that its in my office, I've noticed that there are horizontal lines of "static" moving across the screen. I've been told that this is a sign of interference coming from other devices, but my computer tower is at least 1.5 feet away from the monitor, and the only other device that could be causing it is the electric fan next to me. Somehow I doubt that.
Is there any other way to tell where this interference is coming from?