mystery dvd drive that doesnt exist

my computer has created its own DVD drive. it is listed as “generic dvd-rom scsi CdRom device”. it is listed as Drive ” I “, there is no drive ” I “. i have two drives, on cdrw, one dvdrw, but i have 3 listed. i cant remove this non existent drive as it simply returns, no software I am aware of has installed a drive ( ala gamedrive ), and even if it had, the drive is non-functional, simply there, and is occasionally queeried by the computer. suggestions ?