screen just works correct on the upper 1/3th

halo, is it possible to run the special diagnostics program by myself before bringing the computer to the store.

my screen just works correct on the upper 1/3th, the two parts down just come and go, and flikers or gets a strange gray color with traces of the background pictures.

the external screenn works 100% perfekt

this might be than the problem its on the Nvidia?

i have replaced the display data wire but still get this flickering effects.

my model its the a1260 2,4Ghz bought on july 2008

thanks a lot!