What does the red circle of doom n an xbox 360 mean?

The Red circle on your X-box, or the "Red Circle of Doom" as people like to call it is causedwhen the insides of your X-box begin to melt from heat, or to much playing time. Or both. You can't fix this yourself, so send it back to the makers for a new X-box. They have gotten rid of this problem with newer X-boxes, but older ones still have a chance of getting this.