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All right, I've got a pretty strange one here. Since I installed Windows 7 on this machine some time ago, image thumbnails have never worked properly. For the vast majority of images, they completely fail to show up, showing the icon of the default image viewing application instead. Please note that the “Always show icons, never thumbnails” option in folder options is not checked. I've taken a screenshot demonstrating the problem, here:

screenshot

Sometimes, a few image thumbnails will show up correctly, maybe about one in ten, with the rest failing as well. Another screenshot, with a handful of thumbnails visible, can be seen here:

screenshot 2

Windows Explorer does not appear to make any effort to populate the missing thumbnails, and there is no appreciable CPU usage. I can leave a window with missing thumbnails open all night and they will still never appear.

Newly created images never generate thumbnails, only images that have been on the system since day one will occasionally show them. This leads me to believe that explorer is set to show thumbnails, but whatever process is supposed to be in charge of actually generating them has failed somehow. In previous versions of windows, explorer.exe itself was responsible for thumbnail generation – has this changed?

Any suggestions at all – even if you aren't sure that they will work – are welcome. I'd hate to have to wipe and reinstall on this machine for such a minor annoyance.

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How many images were in the folder? There is a limit of 4,096 thumbails, then the rest are shown with an icon. –  Synetech Feb 24 '12 at 23:42
    
@Synetech: Only about ~2000 in that folder. –  Fopedush Feb 28 '12 at 2:44
    
Too bad you had to resort to reinstalling instead of being able to figure out what the problem was. This person seems to have a related problem. I’m starting to suspect there may be some unusual mechanism that relates to the displaying of icons and thumbnails that some programs mess with. That this question was turned into a community wiki because of the vast variety of attempted answers is a testament to the peculiarity of the problem. :-| –  Synetech Feb 28 '12 at 2:49
    
Yup, I was right; there is indeed another mechanism. Between these two questions (and investigating my own problem with .html icons), I figured out what was the likely cause of all three of our problems. Unfortunately you have already wiped it out, so we can’t confirm, but it’s a pretty good bet that ACDsee was to blame like you suspected; it probably installed an IconHandler. –  Synetech Feb 29 '12 at 4:32
    
Indeed, ta.speot.is brought up the same idea. I regret that I had to resort to a reformat, but I lived with the problem for a good 4-5 months without finding a solution. It is true that a disproportionate number of people who posted in this thread seem to have ACDSee installed, and I can't preclude the possibility that it is somehow to blame. It should be noted, however, that I did try uninstalling ACDSee and the problem remained. Additionally, after the reformat, I installed the same copy of ACDSee, and the problem did not resurface. –  Fopedush Mar 1 '12 at 21:35

5 Answers 5

Checking "always show icons, never thumbnails" (in the folder options menu you see in the asker's screenshot), applying, unchecking and applying again, solved the problem for me.

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Thumbnail generation is initiated by explorer.exe, but applications can register themselves to create the thumbnail. An application simply has to implement http://msdn.microsoft.com/en-us/library/bb774614(VS.85).aspx as a COM object.

For instance, when you are installing the Combined Community Codec Pack you have the option of letting Haali (I believe this is the component) of taking over generation of thumbnails for video files. Thus thumbnail generation is the responsibility of Haali.

Search under HKEY_CLASSES_ROOT and you will see many thumbnail providers (for example XPS and Office Documents).

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I recently had this problem, and i got it to work again:

  1. open the taskmanager
  2. kill explorer.exe
  3. go to File -> new Task, run cmd
  4. navigate to C:\Users\user\AppData\Local\Microsoft\Windows\Explorer
  5. delete all .db files (del *.db)
  6. close cmd
  7. again, in the taskmanager go to File -> new Task, run explorer
  8. done.

I have some shady suspicions that the problem happened while having low free disk space on my main HDD.

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The only correct answer –  nZeus Jul 11 at 12:55

Not sure if this will work as obviously I can't reproduce the problem to test, however this is what I would recommend:

Go to the start menu, expand Accessories, expand system tools.

Click on Disk Cleanup.

Select the primary hard drive (however you may want to do this on others after... but I think the following option only comes up on primary)

Next, Uncheck all boxes apart from "Thumbnails"

Click Ok.

Hopefully this will clean out your thumbnail cache and force them to rebuild whenenver you visit a folder.

If this does not work, in folder options, try clicking on all the "Reset Folders" / "Restore Defaults" buttons as something may have gone wrong on a option that you cannot see.

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1  
Wil- Strangely enough, resetting the thumbnail cache causes all thumbnails to disappear - and then the same few that had already been generated before are regenerated. Images that did not have thumbnails before still do not. It seems that something is causing 99% of the images on this machine to be ignored by the thumbnailer. Resetting folder view settings has no effect. –  Fopedush Nov 17 '09 at 15:44
    
Is there any pattern that links the files together - for example, what are the file extensions? (turn off the "hide file extensions for known file types").... For example, is it all .jpgs, but .pngs are not showing? e.t.c.. –  William Hilsum Nov 17 '09 at 16:03
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There does not appear to be any pattern to which images show up. –  Fopedush Nov 17 '09 at 20:55
up vote -1 down vote accepted

After weeks of fiddling I finally just gave up and reformatted the machine. Problem solved. I have all the same applications installed/configured as before, but the problem did not return. Still a mystery I guess. I wish I had a better solution, but the best I can do is the old fashioned fix-everything reformat and start over.

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That really sucks. I have the same problem and I do not want to have to reinstall. I see that you are also using ACDSee like me, so maybe something in that app is causing the problem... –  cowgod Jan 11 '10 at 21:37
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I had suspected that ACDsee was somehow to blame, but I'm still using it after the reinstall without problems. I'm really at a loss to explain it. –  Fopedush Jan 20 '10 at 19:21

protected by Diago Nov 7 '10 at 8:55

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