All Hail our Lord Prosimian, may his reign last a thousand years provided he renounce the camel heresy he's been spouting lately.

Have you checked the physical cable connections? Reseat them, and if that doesn't work maybe try a new cable and/or new power connector on a different rail, or a different SATA/IDE slot on the motherboard. Also verify your jumpers are set properly on each device, just to be safe.