function IsActiveDeskOn: Boolean;
var
 h: hWnd;
begin
 h := FindWindow('Progman', nil);
 h := FindWindowEx(h, 0,
      'SHELLDLL_DefView', nil);
 h := FindWindowEx(h, 0,
  'Internet Explorer_Server', nil);
 Result := h <> 0;
end;

uses
  ComObj, ShlObj, ActiveX;
 // Check if Active Desktop is enabled (2)
function IsActiveDesktopEnable: Boolean;
 const
  CLSID_ActiveDesktop: TGUID = '{75048700-EF1F-11D0-9888-006097DEACF9}';
 var
  ActiveDesk: IActiveDesktop;
  ComponentsOpt: TComponentsOpt;
  hr: HRESULT;
  dwReserved: DWORD;
 begin
  ZeroMemory(@ComponentsOpt, SizeOf(TComponentsOpt));
  ComponentsOpt.dwSize := SizeOf(TComponentsOpt);
  hr := CoCreateInstance(CLSID_ActiveDesktop, nil, CLSCTX_INPROC_SERVER,
  CLSID_ActiveDesktop, ActiveDesk);
  if SUCCEEDED(hr) then
  begin
  hr := ActiveDesk.GetDesktopItemOptions(ComponentsOpt, dwReserved);
  // ActiveDesk._Release;
 end;
  Result := ComponentsOpt.fActiveDesktop;
 end;