At work, we recently upgraded to flat panel monitors for the registers up front.

One of them has a line going all the way across the screen horizontally... it is about 2 inches [5 cm] up from the bottom... The color of the line will change depending on the on-screen color.

I am pretty sure that it is a defect in the monitor itself... I was just curious as to what might cause that. As far as I know, the line just appeared without any obvious cause. [No abuse to the monitor in other words] ...

Any thoughts, suggestions? Much appreciated.