This was part of my test. I backed up to a USB drive, did a check image immediately and received a corrupt file message. I then removed the drive from the external enclosure and connected it as a slave on the ide ribbon and all of a sudden the corrupt file is okay. There were no other changes other than the connection and changing the drives. Since the drive received the image in good shape on the USB, I assumed the write function of the usb controller and drive were at least good. This narrows the problem to the read function of the usb enclosure controller and/or the software. I conducted another such test using the firewire interface and the results were the same. As the controller in the usb controller is a PL-3705 for both interfaces, it still leaves me wondering if the controller is the problem or is it the software routine. TI8 is the only program showing corrupt data, so I don't think the software can be totally ruled out at this point.