04-16-2009, 06:36 AM
A lot of theories go about the graphics card, and I guess they may be right from time to time.
But, I had for 9 months or so purple horizontal lines coming and going on my 4+ years PB g4 alu, and I noticed they especially would turn up when gif/flash ads containing a lot of orange were showing in a browser.
From time to time the screen would also go entirely black, and, a few weeks ago, it would suddenly just go to sleep mode.
I opened my PowerBook (have done it before, when replacing HD), and noticed after a day or two that it went to sleep every time I covered the LEFT light sensor. Hah. After some searching, it turned out that removing the RIGHT light sensor solved it all. Light sensors are now deactivated, but so what, I have ordered a new right light sensor, and I have not seen the pink/purple lines ever again.
My PB has a ATI 9700 card.
Just an idea that I hope might be useful for someone.