The response code is in itself a major pain, but I hope that CL chose to leave the cydoor out of it. THey used this is Avatar Labs and it killed the floppy drives in a lot of computers that run Windows XP Pro. I speak from experience, it happened to my. The cydoor is, basically, a piece of software that sets itself up as hardware device, uses an IRQ, and must be present for the program to run. Unofrtunately, in XP Pro, the IRQ that it uses is the one assigned to the floppy drive. It was nasty. CL never provided a fix for it. Just pointed people to the manufacturer of Cydoor for the patch.