On my 4th iMac at the moment, love the machine, love what it can do and love the general design but I'm becoming somewhat despondent with what appears poor quality builds. first i3 died in 2 days with hard drive crash, replaced 2nd i3 sent back due to the yellow tinge on the bottom of the screen, took back within the 14 days and money refunded. 3rd and now upgraded to the new version of the i5 and returned after 6 weeks with the same fault as this one which I think I've read is ion contamination? 4th i5 and this is the fault I have which is what looks like grey shading on the inside of the screen, almost like smoke damage but I don't smoke, my home is smoke free and the room where the i5 lives is always kept at around 65 degrees, no damp in here etc. I'm going to be taking it back again and this one is two months old, i dont want to leave it at the shop again as it's just too much time without my mac etc. I have 3 yr applecare anyway but this machine is just two months old. Why is this ion contamniation occuring and is it likely to follow on to the next one I have etc, returning it is a 80 mile round trip and a lug of 800yds to the store through a busy shopping centre which is far from ideal Have Apple confirmed this as an fault (highly unlikely I know), are the new models (newer than Oct 10) rectified? what other choices do i have and given the serious amount of inconvenience I've experienced I'd like Apple to recognise that somehow. The two pics will show major shading of grey around the edge (particularly the right side) and the same in any light coloured background, so what you see looks 'mucky' but that is how the screen looks...disappointing really.