My guess is either you have bad memory stick or the drive is failing, or you are trying to move the drive from one PC to another, which won't work.
Try removing all your memory except 1 stick. If no go, pull that stick and replace it with one of the ones you pulled, try again.
you can save the data from the other HDD by using it with an external enclosure, like a USB external drive. I believe Thermaltake makes a device that allows you to plug in the HDD on top of it, and connects via USB to your PC. It's called BlackX or something like that.