The required anti-forgery cookie "__RequestVerificationToken" is not present

I have a project that is on my server and is working on most machines, but in some the message is being received:

The required anti-forgery cookie "__RequestVerificationToken" is not present. 

I have in my controler:

 [HttpPost]
        [ValidateAntiForgeryToken]
        public ActionResult Salvar(Ramal ramal, HttpPostedFileBase upload, int CallSource)
        {

            ViewBag.CallSource = CallSource;

            if (ModelState.IsValid)
            {
                string AuxExtensao;
                byte[] auxFoto;

and in my view:

@model Ramais.Models.Ramal

@using (Html.BeginForm("Salvar", "Ramais", new { CallSource = (int)ViewBag.CallSource }, FormMethod.Post,
    new { enctype = "multipart/form-data" }))
{

    @Html.AntiForgeryToken()

I have 50 machines ok and two showing this message when the user saves the information. If the same goes in another machine it works ...

Has anyone gone through this?