I was wondering if anyone could tell me what my poor iMac is doing. I bought it off of Kijiji and when it was demo'd before i bought it, it was working fine. Once i got it home and turned it on, i got this on my screen... I turned it off, let it sit overnight, and then turned it on again. This time instead of those lines, it fades from black to green then to a bright white. I am able to turn up and down the brightness via the keyboard *F14 and F15 keys* but that's all i can do. I don't see anything on the screen other than bright white. Is this a problem with the onboard graphics, or is it something else?