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In the last few days, I've been having persistent problems by... something that causes a dllhost.exe process to spawn and consume minutes and minutes of CPU time. Procexp says:

enter link description here

While fascintating, that's really nothing helpful to trace the process back to what summoned it. The other tabs are similarly unhelpful, at least to me.

What's going on? How can I go to the source of this?

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possible duplicate of Windows Explorer crashes when loading a folder. That folder is my desktop - sounds suspiciously simlar, although I'm failing to find obviously bad thumbnail providers. –  badp Feb 8 '13 at 23:58
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2 Answers 2

up vote 3 down vote accepted

Perhaps more helpfully, checking the command line gives me: (line break inserted for your reading pleasure)

C:\WINDOWS\SysWOW64\DllHost.exe \
  /Processid:{AB8902B4-09CA-4BB6-B78D-A8F59079A8D5}

Googling AB8902B4-09CA-4BB6-B78D-A8F59079A8D5 shows this ProcessID to be linked to thumbnail caches. The solution on the internet seems to be to give up on thumbnails entirely. Surely one can do better than that?

By using the handle list feature of Procexp I saw the process (select process, choose View → Lower Pane, look for "File" type entries) I saw in particular that the process had an open handle to this file:

C:\Users\b\Desktop\sigh.wmv

...so I imagine that the issue with thumbnailing videos. Now, Tom Wijsman has already discussed how to handle misbehaving thumbnail providers, but here ShellExView shows no non-Microsoft thumbnailing services!

My current estimate is that this must've been a problem with sigh.wmv in particular, as I generated this file by converting another video file to Windows Media Video through VLC; this file opened just fine in Windows Movie Maker, but the exporting of the relevant project hung at some point in the video.

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Interesting find, thanks for sharing! –  Mark Allen Feb 9 '13 at 5:08
    
I have that very same problem (also a VLC-encoded wmv), and your diagnosis hopefully just helped me solve it! –  Sebastian Paaske Tørholm Aug 1 '13 at 18:23
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There is a Windows 8 fix for this at High CPU utilization by the Dllhost.exe process in Windows RT, Windows 8, or Windows Server 2012 (KB-2853957).

It is caused by Windows trying generate a thumbnail for a corrupt ASF file.

If the hotfix doesn't work (or for anyone on Windows 7), you can fix it like this:

  1. Determine which .asf file dllhost.exe is trying to index:

    a. Download and unzip Process Explorer from Microsoft.

    b. Start Process Explorer (procexp.exe)

    c. In the View menu, check "Show Lower Pane"

    d. Find dllhost.exe in the list of running processes and click on it.

    e. An .asf file should be listed in the lower pane as a "File". That's the corrupt asf file dllhost is trying and failing to generate a thumbnail for. Remember the name of the file for step 4.

  2. Go to the Windows Folder Options and, on the View tab, check "Always show icons, never thumbnails"

  3. Restart the computer. After the computer restarts, you shouldn't have a problem with dllhost.

  4. Find the corrupt .asf file and delete it (or rename it something other than .asf).

  5. You can now turn thumbnails back on in Folder Options.

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