I am having problems with a Wiebetech RTX220-QJ (http://www.wiebetech.com/products/RTX220-QJ.php) which is an external hard drive enclosure for 2 drives. Upon inserting 2 disks (WD 1TB Green drives) to be used as backups, and connecting to my computer both drives were recognized (they had been previously formatted). However, within a few minutes one of the drives (the one in the lower bay) disappeared from the desktop and could not be seen in the Finder or within Disk Utility. I have swapped drives without effect. Regardless of which drive is located in which bay, only the drive in the upper slot is seen. I have also swapped the orientation of the cables -- from computer to upper bay with daisy-chain to lower bay, from computer to lower bay with daisy chain connection to upper bay, and, using two FW 800 ports, one cable to each bay. Same result in either case -- only the drive in the upper bay is seen. I have also connected the drives using eSATA with the same result -- after a while, the drive in the lower bay drops out. If I disconnect everything (remove all cables, including power cable), move the device around (for example, turn it upside down to read the ID, product number, date of manufacture), and then reconnect, I see the drives in both bays briefly. Then within a few minutes the one in the upper bay disappears from the desktop and I get a warning message to the effect that the drive was not ejected properly. I have returned the drive to Wiebetech for repair, and they report finding nothing wrong, so returned it to me. I still see the same problem. At this point, I am ready to return it to the vendor (Amazon.com) in hopes of getting a refund. But if someone has a suggestion as to how to fix this or make it work reliably, I’ll give that a try. I have two other external hard disks (500 GB OWC Mercury Elite-AL Pro) and a NewerTech Voyager Q, all of which work fine with FW 800 or eSATA, and did so with my previous Mac (dual 800 MHz PowerMac) as well as my current machine. The Voyager Q works fine with either of the two drives that I have attempted to use in the RTX220-QJ, using either FW800 or eSATA connection. All of this with the same cables I have used with the Wiebetech device. Any help with this would be much appreciated. Current machine: 2010 Mac Pro 3.33 GHz 6-Core 12 GB RAM 4 internal drives: 2x1TB WD RE3 drives 2x1TB WD Caviar Black drives External drives as indicated in text.