Hi, My iMac G5 20" Rev. B ir experiencing so called "pixel-dancing". In essence, that is when bunch of pixels flash and dissapear randomly mostly on black or dark colors. It seems to be not so common problem, at least google didn't find anything what can help me. Anyhow, the "pixel-dancing" starts usually when iMac been runing for half an hour or so, but then again, it's not regular - sometimes it happens, sometimes it's not, though it seems to happen more often when wathing movies for some period of time (at this point iMac is running about 70 C in fullscreen mode) or working in Photoshop. As I mentioned before, it only happens with solid black, or dark colors. It's really annoying. I contacted our Apple reseller, they suggested to do full time Apple Hardware test - did that, all items passed sucessfully. Anyway, reseller contacted Apple and now is waiting for an answer, so in the meantime, maybe you guys could help? Any solutions, causes or fixes? I made a small video clip showing the problem, here. It's about 30 MB. Sorry about the quality, but the "pixel-dance" is clearly visible. In the video that is Photoshop, with an picture of skating ramp. Thanks a lot.