Оформил: DeeCo
Автор: http://www.swissdelphicenter.ch

uses
   ComObj, ShlObj, ActiveX;

 procedure EnableActiveDesktop(bValue: Boolean);
 const
   CLSID_ActiveDesktop: TGUID = (D1: $75048700; D2: $EF1F; D3: $11D0;
     D4: ($98, $88, $00, $60, $97, $DE, $AC, $F9));
 var
   MyObject: IUnknown;
   ActiveDesk: IActiveDesktop;
   twpoComponentOpt: TComponentsOpt;
 begin
   MyObject := CreateComObject(CLSID_ActiveDesktop);
   ActiveDesk := MyObject as IActiveDesktop;
   with twpoComponentOpt do
   begin
     ZeroMemory(@twpoComponentOpt, SizeOf(TComponentsOpt));
     dwSize := SizeOf(twpoComponentOpt);
     fEnableComponents := bValue;
     // fActiveDesktop := True; 
  end;
   ActiveDesk.SetDesktopItemOptions(twpoComponentOpt, 0);
   ActiveDesk.ApplyChanges(AD_APPLY_ALL);
 end;