If it is a brand new CD-RW and you are going to copy files using Easy CD Creator or Nero etc, no you dont, but if you are going to treat the CD-RW as a big floppy disk using DirectCD or InCD, you do have to format it from within DirectCD or, I assume InCD; I use Easy CD Creator which has DirectCD. InCD comes with Nero. The reason is that the blank CD-RW has no file table structure and formatting is used to create it. You only have to format it once, after that you can add or delete files as if it was a floppy or hard disk. When you have finished writing to the disk and want to remove it, do NOT push the button on the drive, use the program option to eject as it allows the program to close the session and update the file table. This may be your problem if you attempted to write to the disk before and then opened the door yourself. If this is the case reformatting it should solve the problem, but like formattting any other disk you will lose whatever was already on the disk.