K3b uses cdrdao for CD copy up to version 0.10.x. Since the most recent version of cdrdao (1.1.7) does not support ATAPI devices you can only select SCSI devices in the copy dialog. To be able to use your CD-ROM or DVD-ROM as reading device you may either enable ide-scsi or install the cvs version of cdrdao which supports ATAPI devices for reading.