windows 7 - My custom wallpaper is gone, and I can't set any existing wallpaper. Large & extra large icons are blank

Today my Windows 7 Pro booted, but without my custom image desktop image.
The path was correct and image was there (and could be previewed with any software), but Windows didn't display it.
I tried to set it up again, but there was no thumbnails (previews) for it, even for Windows' own wallpapers:

I tried everything I found on Internet, but with no results.

Besides that, there are two strange side effects I noted:

1. There is no icons in "Control Panel\All Control Panel Items\Devices and Printers". But if I change from "Large icons" to "Medium icons", they show right!


2. Not all programs (which should be loaded on startup) are present in SysTray. I checked all missing programs and they have checked "Load at startup" (or similar option) as before. I checked msconfig and there are really missing some items (unchecked).

I checked my computers for viruses (Avira) and malware, but nothing was found.
I haven't installed any software lately.

Addition 1:
I have opened registry key HKEY_CURRENT_USER\Control Panel\Desktop\Wallpaper - it was empty. I have changed it to the path of the picture, and it showed a small icon:

Addition 2:
This is shown when I try to delete a file:

It seems to me that some sort of Windows image engine has some problem?!

Addition 3:
I have found after much digging exactly the same problem at Microsoft site, but without a solution:
Windows 7 - Folder / File icons dont show up in Large and Extra Large Icon view - Medium Size icon view works ok

Answer

Finally I have found a solution for my problem!

There are two registry keys which affect this strange behavior:

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Windows]

and

[HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Windows NT\CurrentVersion\Windows]

In my Registry they were empty, but they should be like this:

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Windows]
"IconServiceLib"="IconCodecService.dll"
"DdeSendTimeout"=dword:00000000
"DesktopHeapLogging"=dword:00000001
"GDIProcessHandleQuota"=dword:00002710
"ShutdownWarningDialogTimeout"=dword:ffffffff
"USERNestedWindowLimit"=dword:00000032
"USERPostMessageLimit"=dword:00002710
"USERProcessHandleQuota"=dword:00002710
@="mnmsrvc"
"DeviceNotSelectedTimeout"="15"
"Spooler"="yes"
"TransmissionRetryTimeout"="90"

[HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Windows NT\CurrentVersion\Windows]
"IconServiceLib"="IconCodecService.dll"
"DdeSendTimeout"=dword:00000000
"DesktopHeapLogging"=dword:00000001
"GDIProcessHandleQuota"=dword:00002710
"ShutdownWarningDialogTimeout"=dword:ffffffff
"USERNestedWindowLimit"=dword:00000032
"USERPostMessageLimit"=dword:00002710
"USERProcessHandleQuota"=dword:00002710
@="mnmsrvc"
"DeviceNotSelectedTimeout"="15"
"Spooler"="yes"
"TransmissionRetryTimeout"="90"

You can make two .reg files in Notepad, fill this and enter it in registry. It works immediatelly, there is no need for a system restart!

Of course, you should make a system restore point, just in case.

Source:
Large & extra large icons blank