some new info on the problem

the problem occurs when the users hits the escape key, causing the mainloop to execute Application.Exit();
i''ve steped that in the debugger, and after this application.Exit, the program keeps executing the main loop, and in the render method, the test on device fails

i think Application.Exit() has GCed some classes, and that''s why i get nullpointerex when i try to access some variables....

but WTF.. isnt Application.Exit() supposed to free stuff, and then exit ?

When you call Application.Exit your form is closed, and it's DirectX device is lost, so it's best to check if the form is still valid in your rendering loop.

while(frm.Created){    frm.Render();    Application.DoEvents();}

Just close the form on an Esc keypress

protected override void OnKeyPress(System.Windows.Forms.KeyPressEventArgs e){    if ((int)(byte)e.KeyChar == (int)System.Windows.Forms.Keys.Escape)    this.Close();}

[edited by - Serge Asperge on March 22, 2004 12:20:32 PM]