I purchased Halo 3 for Christmas. We signed up on line and played for a few hours and had to stop for dinner. When we started it back up, it would not read the disc. Being as it was Christmas break, I rented another copy from BB and it worked fine. We went to the Xbox web page and they have a free replacement program program for Halo. This tells me that Microsoft knows of this issue. Has anyone else had any issues? Has anyone else mailed in their disc for a replacement?