Early Plasma did this easily. It burns the phosphors screen leaving a ghost image.
Brand new tv's have a 200 hour break in period. (if you did not follow this you have probally damaged the screen) If your still in the 200 hour period the other pixels may burn as well and ghost will go away. See below:http://www.plasmatvbuyingguide.com/plasmatv/plasmatv-burnin.html
I'd disconnect the Xbox right away and read my warranty.