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Several hours after each boot the Windows 7 taskbar thumbnail popups stops appear.

Click the currently opened window (it should not be a group of windows) - it will collapse. Than hover the mouse over any other window icon, wait a second, and nothing happens. After that no thumbnail popup windows appear at all.

There is the way to return them back. You need to open two windows of the same application (group of windows), and click their group - two popup thumbnail windows should appear. After that thumbnails are back, until you click currently opened window...

It there a way to fix it?

EDIT: As an experiment I followed the MS Answers forum idea to use Hibernation instead of Stand By mode. And it works! Thumbnail windows are back and stable as they never disappear. The problem is solved. Thanks.

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The example of taskbar thumbnails: blogsdna.com/wp-content/uploads/2009/01/… –  Vasiliy Borovyak Mar 5 '10 at 12:03
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5 Answers

up vote 1 down vote accepted
+150

Check this one:

Windows 7 taskbar thumbnail preview, aero preview not working

and have you troubleshooted?

  • Click Start, type aero in the Start Search box, and then click Find and fix problems with transparency and other visual effects.
  • A wizard window opens. Click Advanced if you want the problem fixed automatically, and then click Next to continue.
  • If the problem is automatically fixed, the window borders are translucent.
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The MS Answers forum have no useful information. And I got same "Troubleshooting could not identify the problem." while troubleshooting. –  Vasiliy Borovyak Mar 9 '10 at 18:10
    
Probably the closest answer to this question. –  Denja Jan 17 '11 at 15:59
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I believe that the behavior you're seeing is by design (Microsoft's design).

Windows Vista introduced Microsoft's Desktop Window Manager (DWM), which is responsible for displaying the thumbnails using composition, which is defined by this article as:

The desktop composition feature, introduced in Windows Vista, fundamentally changes the way applications display pixels on the screen. When desktop composition is enabled, individual windows no longer draw directly to the screen or primary display device as they did in previous versions of Windows. Instead, their drawing is redirected to off-screen surfaces in video memory, which are then rendered into a desktop image and presented on the display.

Desktop composition is performed by the Desktop Window Manager (DWM). Through desktop composition, DWM enables visual effects on the desktop as well as various features such as glass window frames, 3-D window transition animations, Windows Flip and Windows Flip3D, and high resolution support.

Since minimized windows don't update their thumbnails, as they're not being drawn to the screen, any thumbnail you see of minimized windows is actually that of the last repaint of that window before it was minimized.

You must be running some program that degrades or disables DWM, which is responsible for displaying the thumbnails, while all the other windows are minimized. This program can be a full-screen game or any program that degrades the display to Classic Mode.

When you start this problematic program, composition is disabled, and the stored thumbnails are erased (since they're not useful when compositing's off). When that program exits, compositing is turned back on, but the thumbnails are gone : the DWM can't regenerate the thumbnails on its own because the minimized windows are are not being repainted. You now need to un-minimize these windows so they get repainted, and it's that way that their thumbnails get regenerated.

What you're just seeing is an artifact of the way Microsoft designed minimized windows to work with the DWM.

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The idea about DWM and some fullscreen app. is great and can be the cause. But one false thing is present in your answer. If the thumbnail is not available and I hover the mouse other any collapsed window the popup window should appear without thumbnail picture. But in my case no popup windows appear at all. I probably should mention this in my question. –  Vasiliy Borovyak Mar 14 '10 at 8:13
    
@Vasiliy Borovyak: The way of Microsoft are mysterious. Nevertheless, this is the correct answer. –  harrymc Mar 14 '10 at 18:43
    
@harrymc Thanks for this answer -- very helpful. Would there be a way to programmatically force DWM to take new snapshots of all windows? (other than manually restoring windows, or automate a rote maximization of every window) –  Coldblackice May 12 '13 at 8:28
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Killing explorer.exe and then relaunching it using taskmgr restores this functionality for me.

Another annoying symptom of this problem that I've seen is that after hovering over an icon in the taskbar, it will continue to glow with the color W7 calculated for it. It looks to me like this "glow" is only cancelled when the window preview goes away, and doesn't work correctly when there is no preview.

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It's just an annoying bug in Windows 7. I faced it on one of my laptops.

I had to get the latest graphics drivers, but its didn't solve utill i did a full re-install of Windows 7 and then applied the latest graphics drivers

You could get the latest drives and try to install them first, if all fails do a reinstall that ought to work out. It at least worked out on my laptop.

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I already have latest video drivers. And have no possibility to reinstall Windows. But I faced another issue - thumbnail are OK since I use Hibernation instead of Stan By mode. –  Vasiliy Borovyak Mar 14 '10 at 8:17
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Finally figured this one out for me. At some point I had pinned the "show desktop" application to the windows explorer icon in the taskbar. By removing pinning of the "show desktop" the problem went away. Hope this helps.

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