This could be specific to your video card or you could be doing something in the code. Here's a couple of questions to get started troubleshooting this.
When you make a new Windows XNA game and run it, do you get the wonderful cornflower blue screen?
When you run the SpaceWars starter kit, do that run OK for you?
If both of those worked, then we're going to start needing to see some of your specific code. If neither of those worked, then it's sounding like it could be video card related or a potential bug in the framework.