I've noiticed that the cable going between the disk dual and the SWCDX2 is very sensitive to interference. When I first got it I had to re-position the cable a couple times for it to work.
Turn the disk dual and then the SWCDX2 on and then try to access the CD-Rom or Hard drive and when it locks up turn off the SWCDX2 only, and then turn it back on. I had to do this until I got the cable in a good position.