Execute of .bat from does not start with expected user - asp.net

Question

I have the following code:
Dim billy As New System.Diagnostics.ProcessStartInfo("C:\somepath\dumpuser.bat", "")
billy.RedirectStandardOutput = True
billy.WindowStyle = Diagnostics.ProcessWindowStyle.Hidden
billy.UseShellExecute = False
Dim joey As System.Diagnostics.Process
joey = System.Diagnostics.Process.Start(billy)
dumpuser.bat:
echo %username%
net user %username% /domain 2>&1
exit /B 1
I get the following output:
C:\Windows\SysWOW64\inetsrv>echo SERVERXX$
SERVERXX$
C:\Windows\SysWOW64\inetsrv>net user SERVERXX$ /domain 2>&1
The request will be processed at a domain controller for domain xxxxx.com.
There is no such user: SERVERXX$.
More help is available by typing NET HELPMSG 3755.
C:\Windows\SysWOW64\inetsrv>exit /B 1
I would expect the output of %username% to be xxxx\IUSR_SERVERXX because the application pool is set to identity = "xxxxx\IUSR_SERVERXX"
We are using this script to debug the permissions problem, the real .bat file prints to a printer. We are debugging it because the printer "broke" after we changed the identity for the application pool. We have narrowed it down to a permissions problems.
We had other permissions problems on reading and writing files after the change to the application pool identity. Those were solved very simply by changing the permissions on the file. This is different because the script is being executed by a user that is not even defined on the local machine or in active directory on the domain controller.
The question:
How can I get this script to execute as xxxx\IUSER_SERVERXX?

Answer 1

This was a false alarm.
The problem is that .bat is not a reliable way to get the username.
We wrote this c# code and called it in the .bat file as well.
using System;
class Sample
{
public static void Main()
{
Console.WriteLine();
Console.WriteLine("UserName: {0}", Environment.UserName);
}
}
That code output the username we would expect.
We then realized that the problem was not a bad user id, but permissions on the printers.