BlacX Duet. My hard drives keep automatically ejecting.

I have a Macbook Pro and a Blacx Duet connected via usb. My hard drives keep automatically ejecting after about 5 minutes. I get the message "The disk was not ejected properly". I have tied 3 different new disks and have had the same results each time. I have also tried plugging the blacX duet into 2 other computers and experienced the same outcome. I have also tried booting into Windows XP via bootcamp and the drives have continued to automatically disappear. Is there at setting for the Black duet that is causing the disks to shut down? I can hear the drives humming, but not actively spinning or accessing info. Please help