Last night when I was using my Ibook G4 the screen was dimming a little. It would dim just a bit for a few seconds. It not go black or anything. But dim about 30% or so. The whole screen would be even. There was nothing consistent about it as far as I can tell it was nothing I was doing. Just would happen everyonce in a while. I am not really sure what this would be. I was plugged into the wall and the battery is changed. It was almost as if I was running on a low battery. So I am wondering if this is common? Is this maybe a video card going out? I have never had this happen so please for give me for my noobness. I searched around but didn't see anything right off hand that look like the same problem. I know its just the interent and you can't see it. But if there is anymore info I can give just ask for it and I will do my best. Also my iBook has never been dropped so there is not visible damage.