   Drawing disappears after a few seconds - Managed DirectX and C#
  Hi,I'm using DirectX to develop a 2D game engine, using c# as programming language.The game loop looks pretty much like this:while(gameForm.Created){device.Clear(ClearFlags.Target, Color.Black, 1.0f, 0);device.BeginScene();batch.Begin(SpriteFlags.None);batch.Draw(someTexture, new Rectangle(0, 0, 32, 32), new Vector3(0, 0, 0), new Vector3(0, 0, 0), Color.White);batch.End();device.EndScene();device.Present();}The problem here is that someTexture is drawn, but after a few seconds itdisappears, without even throwing an exception.What's happening? I don't have a clue, since I'm a newbie to DirectX.Thanks in advance.Regards.   
  If I activate another window and then activate again my app, the someTexture appears again for a while.Here's how I setup my device:  presentParams = new PresentParameters();  presentParams.SwapEffect = SwapEffect.Discard;    presentParams.Windowed = false;  presentParams.BackBufferFormat = Manager.Adapters.Default.CurrentDisplayMode.Format;  presentParams.BackBufferWidth = 1024;  presentParams.BackBufferHeight = 768;   device = new Device(0, DeviceType.Hardware, frm, CreateFlags.SoftwareVertexProcessing, presentParams);  device.RenderState.AlphaBlendEnable = true;  device.RenderState.SourceBlend = Blend.SourceAlpha;  device.RenderState.DestinationBlend = Blend.InvSourceAlpha;A curious thing happens when I set presentParams.PresentationInterval = PresentationInterval.Immediate. someTexture starts blinking, and it doesn't disappears at all.I hope anybody can help me out on this one, please!.Best regards.   ;  I could solve it by setting creating the device like this:device = new Device(0, DeviceType.Hardware, frm, CreateFlags.HardwareVertexProcessing, presentParams);CreateFlags.HardwareVertexProcessing made the difference.Best Regards.   