The disc has two print areas--an upper area and a lower area. If you have entered information to be printed (using the software), and there is a lot of information, some of it may go into the lower area. For example, on a music CD, the printer may print the title and the artist on the upper area, and a list of songs on the lower area.
When you go to print, the unit will print the upper area, and then stop. At this point, a message should appear on the PC screen prompting you to rotate the disc 180 degrees. After doing this, close the tray, and it will then proceed to print the lower area.