If I recall correctly (which I may not, I may be thinking of non-A2000 drives) there are two pins on one side of the drive and one pin on the other side that actuate switches. One determines if the disk is high destiny, one says it's read-only, and the last one says the disk exists. I have seen it where the disk doesn't seat fully and the pins are right on the threshold. Check that first. But, if you have the same problem on both drives, I would think you have an electrical problem. Try a new cable, and then suspect your motherboard.
