Run another exe, with arguments, and capture output...

Good day...

I've been playing with samples and banging on my head on this, and have given in to ask for help...sigh

From my C# application, I need to run an exe that lives in the %WINDIR% directory, with arguments, and capture the output.

Below is a snippet of what I've tried. Right now, I just want to show a messagebox with the output. The issue that I'm having is ischk.exe is popping up with "Invalid argument". However, if I run the same command from CMD it works fine.

Any help I can get from the gurus would be most appreciated!!! Thanks in advance!

//Create and start the ischk.exe process
                System.Diagnostics.ProcessStartInfo psi = new System.Diagnostics.ProcessStartInfo("ischk.exe");
                psi.Arguments = "-s " + strenv;
                psi.RedirectStandardOutput = true;
                psi.WindowStyle = System.Diagnostics.ProcessWindowStyle.Hidden;
                psi.UseShellExecute = false;
                System.Diagnostics.Process ischk;
                ischk = System.Diagnostics.Process.Start(psi);
                ischk.WaitForExit();
                ////Create a streamreader to capture the output of ischk
                //System.IO.StreamReader ischkout = ischk.StandardOutput;
                ischk.WaitForExit();
                if (ischk.HasExited)
                {
                    string output = ischkout.ReadToEnd();
                    MessageBox.Show(output);
                }