strange skin behaviour

[David198502]

hey skin-experts!
im fiddling around with my first skin for COD.so far so good.i do it with gimp.
i wanted to see the results of my painting skills, so i opened cod and looked in plane option to see my skin.everything was as expected except the nose of the prop.i added a spiral on it, but it doesnt appeared in the menu(it was just pitch black).however i flew a quick mission with that skin, to see more of the details of my skin,and ingame, the spiral on the prop-nose suddenly showed up.
so i decided to land, to look at the skin when its not moving, so its easier to examine my artwork.so i turned off the engine and made a smooth landing.while approaching the runway, the prop decreasing is revolutions due to decreasing airspeed, i noticed that the spiral suddenly disappeared and turned into a black one.i tried it several times with different video settings to see if may be the resolution, texture or shading details are causing it, but even with everything maxed out i have this annoying effect.
sorry for my poor english but i add a picture of it that you guys know what im talking about.
http://www.google.at/imgres?imgurl=h...w=1280&bih=930