When I turn off my XBOX 360, the power button on the console still flashes green

every few seconds? When I turn of my XBOX 360 the power button on the console still flashes green every few seconds. Its not loud, its sounds like the XBOX when I'm playing an Arcade game on it. I unplug the power source and plug it back in and it stops. Should I continue doing that, or should I send it back in? The system works fine when I play it, it just doesnt turn off. The screen on my TV goes off, but the XBOX is still on, I don't understand.
I think you guys are right! I have my iPod plugged into the USB port! I'll try turning it on and off with the iPod in and out of it. Im so excited
Holy ****! You guys are the greatest answerers ever!!! I have Rainbow Six Vegas downloading!!!
I disabled the demo and took out the iPod and now its fine. This is gonna be hard to choose the best answer.