I'm a noob to the game dev world and recently finished the 2D XNA tutorial from http://www.pluralsight.com.

Everything was perfect until I decided to try the game in Fullscreen mode. The following code was added to the Game1 constructor.

        graphics.PreferredBackBufferWidth = 800;
        graphics.PreferredBackBufferHeight = 480;
        graphics.IsFullScreen = true;

As soon as it launched in Fullscreen, I noticed that the entire game was tinted. None of the colours were appearing as they should. That code was removed, the game then launched in the 800x480 window, however the tint remained.

I commented out all my Draw code so that all that was left was

        GraphicsDevice.Clear(Color.CornflowerBlue);

        //spriteBatch.Begin();
        //gameState.Draw(spriteBatch, false);
        //spriteBatch.End();

        //spriteBatch.Begin(SpriteSortMode.Deferred, BlendState.Additive);
        //gameState.Draw(spriteBatch, true);
        //spriteBatch.End();

        base.Draw(gameTime);

The result was an empty window that was tinted Purple, not Blue. I changed the GraphicsDevice.Clear colour to Color.White and the window was tinted Pink. Color.Transparent gave a Black window.

Even tried rebooting my PC but the 'tint' still remains. I'm at a loss here.