Extremely odd. Open up an application like Word or Wordpad, maximize it, and type in text or open a document. Resize it and move it around the screen. Does the pattern follow the text or is it always in the same spot. If it follows it around start digging around in your settings. Try changing the refresh rate and color depth. I'm grasping at straws here too. Good Luck.
Oh, is the cable to the monitor near any source of power or potential interference?