I purchased a 27" iMac late 2012 in April. The first one had a dead pixel, so I returned it. The second one had a dysfunctional disk, which made it crash every 10th—15th minute (also after a clean install). I returned it, too. My third iMac had a dead pixel — that's what I thought at least. But I decided just to keep it, although I hate dead pixels. It was my third iMac after all. But, as it turns out, I noticed today that the "dead pixel" moves around depending on the viewing angle. Technically, it therefore can't be a dead pixel. So, is it just dust under the glass? And is there anything I can do to remove it? Edit: Added two photos. Notice how the black spot is moving from below the "u", and then to below the "o", depending on the viewing angle.