Cant change desktop background

I just now got over a virus and deleted it but after that it doesnt allow me to change the desktop picture at all. The original picture shows up for a second on startup and then goes black. It also shows up just before log off too. Can anyone tell me how to solve this issue? Thanks.

Have you tried to select no image, if it works then delete your picture in the background adn then try to add them one more time. I think that it might have got infected before.

Follow the below steps:

1. First of all click Start - Run - type GPEDIT.MSC and press Enter
2. After that try to expand to User Configuration - Administrative Templates - Control Panel - Display
3. Now check on the right-side pane double-click the entry "Prevent Changing Wallpaper"
4. After that check if the value is set to "Not Configured" or "Enable" then set it to "Disable".

Also check the below link:
http://support.microsoft.com/kb/921049/

Thanks but that didnt work. I have tried another method or regedit from Start and run but it gives me an error that is mentioned below:

16 bit MS-DOS Subsystem
C:windows\system32\REGEDIT.com
C:windows\system32\autoexec.nt. The system file is not suitable for running MS-DOS ans Microsoft Windows applications. Choose 'close' to terminate the application.

Um, I have this problem on my computer, and I try to follow this path:
HKEY_CURRENT USER/SOFTWARE/MICROSOFT/WINDOWS/CURRENTVERSION/POLICIES/SYSTEM

But when I open my policies folder there's only a folder named Explorer, and nothing named System...is there any other way to fix this problem then? And do I have a bigger problem to concern myself with not having the System folder? Any help is greatly appreciated, thank you.