16位ms-dos子系统;错误

我编译了这段代码，没有错误。但是当在命令提示符中运行EXE时，出现"错误"16-bit ms-dos subsystem"错误"对话框。我不知道为什么，因为在我更新Windows XP之前，它工作得很好。

代码有什么问题吗?

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Net.Mail;
using System.Net;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            var fromAddress = new MailAddress("aaa@gmail.com", "System");           
            var toAddress = new MailAddress("bbb@gmail.com", "Receiver");
            const string fromPassword = "xxx";
            const string subject = "Message";
            string body = args[0];

            var smtp = new SmtpClient
            {
                Host = "smtp.gmail.com",   
                Port = 587,                      
                EnableSsl = true,
                DeliveryMethod = SmtpDeliveryMethod.Network,
                UseDefaultCredentials = false,
                Credentials = new NetworkCredential(fromAddress.Address, fromPassword)
            };
            using (var message = new MailMessage(fromAddress, toAddress)
            {
                Subject = subject,
                Body = body
            })
            {
                smtp.Send(message);
            }
        }
    }
}