my iBook started getting the funny lines then it would blink full colors on the screen, would usually happen when i moved it...i read up on it and heard there were problems with the video chip developing cracks in the solder joints due to age and vibration and this is why i would lose my screen. it got to the point to where it wouldnt even turn on at all (the screen) there are a lot of videos on youtube about how to "reflow" the solder, like putting a small cup of alcohol on the chip and lighting it for so many seconds, others say use a heat gun, i tried all of them and none of them worked, i was in the same boat as you and was about to give up, but decided to try one last time with a soldering iron. I took the iron and held it against the legs of one side of the chip, waited till i saw the solder change (somewhat liquify) and then took the iron away and pressed down hard on the chip and repeated to the other side, let it cool down and tried it again, and it worked. so not sure if this is what you were experiencing but it worked for me...good luck.