[ecfisa]

Hola champy.

Proba de este modo:

Código Delphi [-]
function MicroSDPresent: Boolean;
var
  i    : char;
  FName: string;
  Error: LongWord;
begin
  Error := SetErrorMode(SEM_FAILCRITICALERRORS);
  Result:= False;
  for i := 'D' to 'Z' do
  begin
    if GetDriveType(PChar(i+':\')) = DRIVE_REMOVABLE then
      Result:=  CreateFile(PChar(Format('\\.\%s:\%s',[i,'prueba.txt'])),
      GENERIC_READ, 0, nil, CREATE_ALWAYS,
      FILE_ATTRIBUTE_NORMAL, 0) <> INVALID_HANDLE_VALUE;
  end;
  SetErrorMode(Error);
end;

// llamada:
...
begin
  if MicroSDPresent then
    ShowMessage('MicroSD presente')
  else
    ShowMessage('MicroSD ausente');
end;

Saludos.