It is possible you may have a faulty hard drive. Download diagnostics from the manufacturer's website to run tests on the hard drive first. They should offer windows diag. or DOS diag. You don't need to be in windows to run the DOS diag. So you should download that one.
If the hard drive passes all of the diagnostics test then you most likey need SATA drivers. You should be able to get those from the manufacturer's website as well. (I believe SATA drivers are different from your motherboard drivers, I could be wrong there though) If the hard drive fails the diagnostics test, then you should replace the hard drive. I have a similiar issue with my hard drive, every now and then my PC doesn't recognize it, and I ran diagnosticts on it and it failed them, so I need to buy a new hard drive. I'm taking my time doing it because I have a lot of data to back up.
I have a custom made PC, with XP Home OEM. Since I lost the CD, I borrowed a friend's, but used my own product key. This seemed to be okay, untill it said something about having no hard disk/drive.
I looked this up on the internet and people have mentioned SATA drivers. I think this is related to the motherboard?
So will everything be okay if I get the SATA drivers for my motherboard?
How do I find these? I looked on the Asus site, and it seemed too confusing.
Incase you need to know, I have an Asus P5RD1-V
Thank you for reading this by the way!!! 
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