title: Changing screens in XNA
body: <p>In my WP7 game I have a menu screen that remembers information so I leave it going and just create a new game level screen (it's a tower defense so the game is segmented into levels) that is shown over the top of the menu screen. Then when you beat that level I call this.ExitScreen(); (and have also tried ScreenManager.RemoveScreen(this);). It removes that level screen and shows the menu again but I see a flash of purple which is just the default color or the null background or however you want to put it. I don't understand why that purple is flashing. Should my menu screen be right below? I'd be grateful for any help understand what's going on here.</p>