My best advice currently, is to back up\save ALL files etc you can't afford to lose, currently I suggest doing that before any of this, worst case if something goes wrong you wont have lost anything, this is just in case you accidentally get the system to fully reinstall, see if any of this yields any results, beyond this I would have to let those who know more than I carry on, as such issues I would have to get my hands on it and just stumble around, whereas the other guy's know this deep level to make any suggestions that may help more than I can, so see how this goes, then we can go from there.
Cld, 8210Guy has summed it up here in this quote and it may be best to follow his advice. But lets take 1 step back and as the saying goes, we may be like a dog chasing his tail.
Have you tried what I suggested in post 9, it may be best to do so because this would eliminate all possibilities of a bad drive and tbh this is the best way to go. If the drive proves to be good then you have to get more help from the tech's here to see what other causes may be.
It could be a bad controller but not sure if this may be your case or not. In any event if the drive proves to be good then setting the system back to out of the box state might be your option. Some systems I have seen have the ability to reset the system basics\drivers without formatting the system, or if you have a disk, you can select to repair the system, as opposed to reinstalling it, so have a look for any such recovery options, if it's store bought it should have built in recovery.
But bottom line before spending more time of chasing a wild goose, lets try what I said in post # 9 to rule out this drive.
Jimbo1