Impersonating in .net windows forms (C#) & opening a file via Process.start

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C#

process

impersonation

Hello, I'm doing this:
1- Using impesonation (...)
{
2- define process info (filename = path/winword.exe, arguments
= myfile.doc)
3- ProcessStartInfo.LoadUserProfile = false
4- ProcessStartInfo.UseShellExecute = false
5- process.start
}
and I'm getting this error:
"There is not enough memory or disk space to run Word."
Thanks in advance

The code is:

using (new Impersonator(user_name, domain, password))
            {
                System.Diagnostics.Process proc = new System.Diagnostics.Process();
                proc.StartInfo.UseShellExecute = false;
                proc.StartInfo.LoadUserProfile = false;
                proc.StartInfo.FileName = "C:\\Program Files\\Microsoft Office\\Office12\\WINWORD.exe";
                proc.StartInfo.Arguments = path + filename
                try
                {
                    proc.Start();
                }
                catch (Exception e)
                {
                    MessageBox.Show(e.ToString());
                }

            }