Roxio CDR4 is a software component associated with certain versions of Roxio's CD/DVD burning software suite. The "CDR4" typically refers to the Roxio Easy CD Creator 4 software, which was a popular tool for burning CDs and DVDs in the early 2000s. The software includes a set of drivers for optical drives (CD and DVD drives), and the "Roxio CDR4 Windows driver" you're referring to is likely the driver used for communicating with and controlling these drives.