Shadows in Photos

Let me first say that I am a beginner. I was trying out my new Canon EFS 10-22mm wide angle lens with lens hood last night at a local highschool football came. I have the Canon T1i camera and was shooting in full auto mode. I kept noticing a dark shadow at the bottom center of the photo after I took the picture. I was using the built in flash on my camera. I removed the lens hood but still was getting the shadow in some of my photos. Any ideas?

The lens is getting in the way of the flash. Smaller lens and/or higher flash. - TF

Agreed. It's actually obscuring the flash, causing the shadow. Try an external flash which fits on the hot shoe and sits higher on the camera.