Try the reg file fixes on line 187 at the link below.
Restore Themes Functionality
Restore Classic Theme
Save the REG File to your hard disk. Double click it and answer yes to the import prompt.
I run a Dell XPS M140. I'm ready to pull my hair out. Three days ago I was infected with the "AV Security Suites" virus. I immediately shut down my computer, restarted in Safe Mode With Networking, and ran every single thing I had. I ran Avast, Spybot, Ad-aware, Malwarebytes, CCleaner, Registry Mechanic, Advanced System Care, and Glary Utilities. I thought I got it. I restarted my computer in normal mode and all seemed well until I noticed I cannot change my desktop theme or wallpaper. When I change the theme to "Windows Classic", it works, but when I restart my computer it's right back to the XP theme (green start button/blue taskbars)
My wallpaper is blue. I have searched forum after forum and have tried it all. If I choose a picture, right click set as desktop, I see the preview of what it SHOULD look like, but when I click "apply" and then "ok" nothing changes. Here's a screen shot http://i34.photobucket.com/albums/d123/corabell99/untitled.jpg
And just to save you the trouble, here is what I've tried:
"Open Display Properties.
Click the Desktop tab.
Click the Customize Desktop button.
Click the Web tab in the Desktop Items window.
Make sure all checkboxes in this window are un-checked including My Current Homepage.
Restart your computer.
Check to see if you now can change your desktop background.">>>>> Didn't work.>>>>>
Also tried: "erase everything under the folder in your registry (HKeyCurrentUser/Software/Microsoft/Windows/Policies)
except the default key which is inside of the policies folder, and the subfolder called "Explorer". In the Explorer folder should be only two keys, the default key and one other key which reads:
NoDriveTypeAutoRun REG_DWORD 0x00000091 (145)">>>>Also didn't work.>>>
Also tried this with (HKEY_LOCAL_MACHINE_\Software\Microsoft\Windows\CurrentVersion\Policies\System)
Please help! I think my biggest fear is that there may be something lingering behind from the virus and I'm half-afraid to use it!