Blurry lines running down TFT?

[Atari]

Hi all,

I've just turned my Samsung 913N on today, and I've noticed that there's lines running down the screen where text and images become blurred when passed under the line. The lines themselves aren't visible, I know they're there because anything displayed under the lines becomes blurred and looks almost as if the fonts were bold.

I've been using the monitor on this graphics card for the last few months, and this has never been there. Any idea's what could be causing it?

Thanks