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I have a strange problem. I am very good with Macs and all Apple products, but this one has me stumped.

I have a new (4 months old) 27" iMac (2.7 GHz Intel Core i5) with Lion 10.7.2

and it works beautifully, but it does one thing that drives me crazy. After it has gone to Sleep, and I wake it up to use it, the screensaver pic or Lion Grey linen image stays on the screen and I have to scrub away some of it with my pointer/cursor to see the user login screen, almost like scratching away some frost to be able to see through my car's windshield in the winter.

What is causing this? And what can I do to get it to stop? I have had Macs forever and have never had this problem.

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Are you still facing this issue? (We encourage answering the question or editing the best answer if you find one close to the solution or one that led you there...) –  bmike Dec 9 '12 at 7:01

3 Answers 3

I see this same problem. I see it on both user accounts on my 2011 iMac when the screen saver has been active and the user is automatically logged out. If the user logs themselves out this isn't present.

I don't believe it's a problem, just a video driver quirk.

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It sounds like an issue with either the WindowServer or the Screen Saver service. I don't know of any way to resolve this other than reinstalling Lion. There may be a UNIX guru out here who can do some magic with the system files, but I'd recommend getting a solid backup of your data and reinstalling Lion using the recover partition.

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I appreciate that answer very much. Anyone else have any thoughts or theories? –  MarkTap Jan 12 '12 at 2:02

I am experiencing this exact problem (aka "video crash/corruption"). This appears to be a rather typical manifestation of vid card driver -vs- OS & graphic app(s) mapping conflict. (mine is ATI Radeon HD 5670 512 MB on 27" iMac 8GB running OSX Lion with latest updates)

So, the fix is wait til someone "blinks": either APPLE or AMD-ATI - and then download the new driver/OS "fix" from the respective site. As of this writing, don't yet see any.

Either that or get a new vid card with compatible drivers.

PS: The ubiquitous "reinstall OS..." will only waste your time if this is the cause.

One other possibility, especially with Lion not auto-installing some things such as new Java stuff and also the usual need for the update of "support apps" such as Adobe Shockwave - in case the Lion screensaver & Login screen/util make use of these - would therefor necessitate downloading the updates for these direct from the publisher.

-Best Regards.

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It may be interesting to try the 10.7.3 update that was just released, which has the following in it's release notes: Address a graphics performance issue after sleep on some earlier iMacs that use ATI graphics –  stuffe Feb 1 '12 at 21:51

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