I posted a thread a while back about my iBook G4's screen blinking and going white. I took it to the Apple store and the guy there said it's most likely a logic board issue, but could possibly be due to the fact that it needed more memory. I bought new memory and upgraded it from 512MB to 1.5GB. It's much faster now, but still blinks and turns white. Then I ran the hardware test that came on the install disc 1 twice. It said that all the hardware was fine, including the logic board. What else could it be? Any ideas?