Since a couple of days I experience some strange graphical artefacts on Snow Leopard. Usually after a certain uptime, the background image would show some strange colours at some place. This could be reverted by reloading the background image. But the problem would appear again after rebooting (and waiting for an indefinite time).

Sometimes, the shadow of windows would also have some artefacts; and this time the application switcher is completely distorted.

Any ideas where I need to search for a solution of the problem?

enter image description here

Edit: Model: MacBook Gen. 3.1 / all updates installed

Update: After not having used Safari for a while, the problem has not occurred anymore (at least not after 20 days of uptime). Could well be that the problem had its origin in Safari or a Safari-related plugin. (Possibly Flash or Click-to-Flash as it did not happen with both deactivated, though the running time with this configuration might have been to short to be of any validity.)

  • Wow, that's bad. Did you install any updates recently? Does this appear even on external monitors? – alex Jan 22 '10 at 19:02
  • Concerning updates, I’m almost up-to-date. (Except for the update that came in just now – now when I reboot, of course the problem will vanish for an unknown amount of time. I’ll try to find out exactly when it happens again.) Unfortunately, I don’t have an external monitor to try there. – Debilski Jan 22 '10 at 19:09
  • Just as an aside, in case you wonder: assuming you made the screen capture using that same Mac, it's not the LCD screen itself that is faulty. (So, the answers below about a faulty graphic card are probably right.) – Arjan Jan 25 '10 at 12:22
  • Hardware problem. Safari could not possibly cause this. – Hasaan Chop Mar 22 '10 at 14:32
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    @Cawas: I removed Click-to-Flash and it has been fine since then. – Debilski Mar 27 '11 at 1:44

There's a recall on MacBook Pro's from early 2008 with faulty graphics cards. You don't mention what type of machine you use but it's possible yours is one of them.


  • +1 Because I think it's either a problem with a faulty graphiccard or and heat problem. – Bobby Jan 25 '10 at 14:04

I am getting the same artefacts on my system sometimes the icons on the desktop or the dock and sometimes on the title bar at the top of the screen, but have found they go away if I relaunch finder/windowserver/dock!!! I would assume this would rule out a hardware problem, also if I carry out a clean install of OS X then the problem goes away for a couple of months. Any suggestions?


  • yes, probably not a hardware problem that only amazingly affects the icons in the task switcher :) – Dan Rosenstark May 15 '10 at 18:47
  • I have stopped using Safari (and Click-to-Flash) for a while now and the problem has not occurred anymore. So, I doubt that it’s a hardware issue in my case. – Debilski May 16 '10 at 0:55

I had the same problem with my MBP. They have documented problems with the NVIDIA cards, but my problem was like yours and not the more popular and widely addressed problem. I had to keep going back to the "genius" bar, and when I finally talked to the head "genius" he was able to test for a "rare" problem, and that was what it was. I have always said, "if you hear hoof-beats think horse, not zebra," but in this case I definitely had a zebra in by machine.

  • And how can I test for this zebra condition myself? – Debilski Jan 24 '10 at 13:35
  • You would need the latest version of the "Apple Service Diagnostics" image and be able to put that on a bootable USB key. This is non-trivial and costs money. I was not able to download that program, so I ended up needing to go to that apple store myself. – gavaletz Jan 24 '10 at 15:14

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