b) Manually (XP -Pro) :
1. Start > Run > gpedit.msc
2. Under User configuration > Click [Administrative Templates\Control Panel\Display\]
3. There will be a value named "Prevent changing wallpaper" > Set it to "Not Configured"
--- or ---
c) Manually (XP -Any) :
1. Open Regedit
2. [HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\ActiveDesktop]
3. Double click the value named "NoChangingWallpaper" > Set it to 0
4. [HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Policies\ActiveDesktop]
5. Repeat Step 3
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