Greyish Smudge marks behind the glass screen.

Do you mean replaced iMac or just the display itself?

Ditto here with iMac 24, 13 month old .. grey smudges + APP = LCD promptly replaced, but, with a tongue-in-cheek mention of 'environmental effect' clause .. DVD drive replaced too. Sweet, ness!

Still battling 'sudden' shutdowns (shut-off's actually) ... not necessarily temperature related, but definitely caused by partly-intensive audio/video scrubbing AND strangely, since the LCD replacement a couple days ago - every time that 'quicktime' or QT 'new movie recording' is launched .. waiting for some on-site TLC as promised by our friendly neighborhood 'Anything Mac' folks

Same story, different computer. We are now on our second computer with the same issues. Gray marks that start in the upper right hand corner and spread across the screen to the left and down the right side. PAID for the applecare and now they insist that it is not an issue with the computer, but it is an issue with our house! She said that they will service the computer one more time, but no more for this issue, an issue that has come up way too many times with other imac owners to simply be an "environmental issue" in our houses. It's my feeling that they know there is an issue with these computers and they keep telling us the same thing to put the blame on us and not their machines/design. I have a $300 air purifier with a HEPA filter in our house and she claims that it might be dust. If the air purifier doesn't take care of the dust issue, I don't know what apple expects from the environment of the people who are going to be using their computers. She also suggested that I could dust more....interesting. I'm taking it in today for service for "the last time" with 2 print outs of other posts just like mine (just a couple of the 14 pages here). I have a bad feeling that this will happen again, but I will cross that bridge if I come to it. Like most of the people here, I like this computer and want it to work. We paid a lot for our machines because we believed that apple made high quality products that they would stand behind (and not place the blame on us and tell us we need to dust more often- she didn't have much to say about the fact that we have a HEPA air purifier running 24/7). I understand that there will be issues with products and they will not be perfect, but when it happens I expect a company like apple to make it right, not pass the buck. Maybe a new product line: The ibubble- an overpriced plastic dome to create a sterile environment in which to use our imacs.

the glass panel of the imac is basically a baaaad idea. looks good, but from a functional viewpoint it's terrible. form over function! 😟

Late 2009 27" imac and the "smokey" grey smudges, so no warranty anymore. Also don't have Apple Care.

Bought the mac Dec 2009, noticed the smudges in April 2011, been using the computer everyday.

Looking for tips and information about how to go about this one. Contact Apple or go directly to authorized service? What's the European pricetag for this? Since this is a wide spread issue, wouldn't want to throw money at something that should be covered even when warranty is gone.

Updating my previous post. I did get the LED screen replaced through Apple Care. They gave me the same company line that they have given everyone else regarding Environment and Condensation problems etc.But they did agree to get it fixed. Here in Melbourne, Australia, Apple use Unisys for their Tech support and a Technician come out to my house to undertake the replacement. I asked him if he had done many replacements due to the Grey smudges,he reluctantly said he had done a 'few'. I watched him whilst he was dismantling my iMac and when he removed the LED panel, I took a look at the 'Guts' of the machine. Low and behold right where the smudges on the screen appeared they coincided with the Heat transfer Bar that runs from the Heat sink to what I believe to be the Video Card (on the right hand side of the iMac). There is also a similar arrangement on the left hand side. Could this be part of the problem that we all seem to be experiencing?

It is strange that we are discussing a major problem on an Apple discussion site and no one from Apple has attempted to give us an expanation.

If there is any one from Apple out there, please have the courtesy to respond to this problem and give us a valid explanation. The paying Public should not have to put up with this.

I have the same problem with my iMac 27" too and it is getting more and more prominent on the right side of the screen with each day passing by. I bought this machine a few months ago. I also see yellow tinge on the bottom right corner. Being a professional photographer, this is not acceptable at all and it majorly hampers my work. 😟

I will be contacting the customer care soon. I hope Apple comes up with a permanent solution for this problem asap!

Yet another person with this problem, noticed it the other day when I had a textmate window open in the top left hand side. Not too bad at the moment but as soon as theres anything with a light background you can notice it. Next time I'm near the Apple store I'm going to go in and mention it to them and see what they say, it's still under a year old so hopefully get a replacement display.