This article describes an issue with the Disc Burner 1.x CD-RW software installed on Apple products containing a CD-RW drive such as the Power Mac G4 (Digital Audio) and iMac (Early 2001) computers.
Each write to a recordable media, such as CD-RW, is called a session. Single session is the ability to write to a disc once. Multiple session allows you to write to the disc multiple times without reformatting.
Disc Burner 1.x will not rewrite to a CD-RW disc without first reformatting the disc. Once data has been written to the disc, no further writes are allowed until the disc has been reformatted.