Logoff doesn't work through windows service

Question

Dear Friends,

I am facing this problem on Windows 2003 and 2008 Server. On XP it works fine.

I have written and Windows Service that takes receives the command and executes tasks such as Logoff, Shutdown, etc.

All the commands except Logoff works fine. I tried following ways to perform the Logoff. However it didnt work.

Try 1:

                Process.Start("shutdown", "-l");

Try 2:


    [DllImport("user32.dll")]
    public static extern int ExitWindowsEx(int uFlags, int dwReason);

    ExitWindowsEx(0, 0);

Try 3:

    Process _currentProcess = new Process();
               _currentProcess.StartInfo = new ProcessStartInfo("shutdown", "-l -f");
               _currentProcess.StartInfo.UseShellExecute = false;

                _currentProcess.Start();

Try 4:
    Process.Start("logoff.exe", null);


If I write a simple C# based applicatin (not Service) it works fine for all the tries that I have made.

I am facing this problem only when I put this code in Service and that to on 2003 and 2008.

Any pointers will be appriciated.

Thanks,
Vinayak.