[angvelem]

Код:

var
  StartInfo : TStartupInfo;
  ProcInfo  : TProcessInformation;
begin
  ShellExecute(0, 'Open', PChar('D:\Program Files\Mozilla Firefox\Firefox.exe'), '', '', SW_SHOWNORMAL);
  
  FillChar(StartInfo, SizeOf(TStartupInfo), 0);
  StartInfo.cb := SizeOf(TStartupInfo);
  StartInfo.dwFlags := STARTF_USESHOWWINDOW;
  StartInfo.wShowWindow := SW_HIDE;
  if CreateProcess(nil, PChar('D:\Program Files\Mozilla Firefox\Firefox.exe'), nil, nil, False, HIGH_PRIORITY_CLASS, nil, nil, StartInfo, ProcInfo) then
  try
    if WaitForSingleObject(ProcInfo.hProcess, Timeout) <> WAIT_TIMEOUT then
      TerminateProcess(ProcInfo.hProcess, STATUS_TIMEOUT);
  finally
    CloseHandle(ProcInfo.hThread);
    CloseHandle(ProcInfo.hProcess);
  end;

Вот навскидку.