I realize this is an old question but it seems like a lot of people never got it resolved. So I'm going to add my two cents in the hopes that it helps some new comers to the thread.
This problem could be for any number of reasons as it appears to be an equal opportunity annoyance. So I do suggest that anyone who is coming here for this reason try ALL of the suggestion that are posted here.
The easiest and simplest fix is IF you know approximately when the problem started - e.g. if you changed some settings and noticed fairly quickly that's when it happened you can do a system restore to a date prior to making those changes
to see if that works.
Here some basic stuff that some are asking how to do:
Verify your picture folder settings are correct: In My Pictures go to Tools/Folder Options/View. Under Files and Folders -
Uncheck the box that says **ALWAYS SHOW ICONS, NEVER THUMBNAILS.**then save or ok.
To open picture: Highlight the picture you want to view. Right Click and choose Open With/Choose Default Program and look for the Windows Photo Viewer icon. If you don't see it then click on the tiny box with the cross in it - should be bottom right of the box your viewing. If you still don't see it then
hit the browse button and locate the program and click on it. This will put the program with all the others and then check the box that says
Always use the selected program....etc.
To open an elevated command prompt - first locate the command prompt. I believe its in the Accessories folder. In
Windows 7 go to Start/All Programs/Accessories. Highlight the cmd prompt icon and
Right click on it. When the menu opens the Run as Administrator is near the top in 1st, 2nd or 3rd place. Click on that - (if you have set a password for the administrator it will ask you for your password) now you are in an
"elevated command prompt" which just basically means you can tell it to do what you want. btw You can run any program on your pc as the Administrator. Office, Excel, Adobe Photoshop, Viewer, etc. just right click on the program icon.
For some it might be a permissions issue so make sure that you have given yourself
full control over the Photo Viewer program as well as the
My Pictures folder or whatever folder you put the pictures you want to view in. Its best if you go to the parent folder - for example in
Windows 7 the Photo Viewer program is inside Program Files meaning: Program Files/Windows Photo Viewer/ImagingDevices.exe The parent folder is Program files. So Right Click on Program Files. Choose Properties/Security then highlight the
administrators group in the top box. If no check mark is next to Full Control in the bottom box (permissions for Admins) then click the Advanced button at bottom. The 1st tab is Permissions highlight the Administrators name, click the Change Permissions button.
Again highlight the Admin name, click edit, make sure the correct user name is in the name box, click on the arrow and choose "this folder, subfolders and files" then click Full Control and ok.
Now check the Include inheritable permissions and the Replace all child objectand ok. (you can also do this before you go into edit just make sure the correct user name is highlighted when you tick the boxes) The wizard will start and you'll see it working but some folders will stop and say access denied or something like that.
Click Continue and keep doing that every time it asks you to. When it finishes click ok until the properties box closes. Then go back in again and highlight your admin name to make sure the Full Control checks are there. Do this with the My Pictures folder
as well.
I hope this helps new people that came here because they have the same issue.