Yeah! Figured out how to get informed about the windows system shutdown/user logged off in .NET. With the knowledge of my VB6 days (there we get the info as a parameter in the window close event) my research goes completely to the wrong direction and a search via google does not point to a similar solution for .NET.

The may be simplest code to use is this:

public class Form1: System.Windows.Forms.Form {
  // Constant value was found in the "winuser.h" header file.
  private const int WM_ENDSESSION = 0x0016;
  ...
  protected override void WndProc(ref Message m) {
    switch (m.Msg) {
        case WM_ENDSESSION:
          // Save settings, state whatever here...           MessageBox.Show("WM_ENDSESSION received.");           Application.Exit(); // exit the normal way           break; // never reached
    }
    base.WndProc(ref m);
  }
  ...
}