Acer travelmate 4500 screen problem

Hello, i have a acer travel mate 4500 its about 3 years old, fantastic bit of kit, until yesterday....
its runnig xp. the screen is white which is good! but has a aqua/green shading on the majority of pixels, sometimes, the whole screen goes this green colour, which in fairness aint that bad, i can see quite clearly, only thing is watching video is garbled at best. i have hooked the laptop up to my desktop monitor, and the sane thing appears on the desktop monitor, which would suggest that the screen itself is not the problem?

any suggestions, is it a invertor or video card??
kind regards