Hey there, Sherry.
This is not a very good sign indeed. It could be an HDD related issue. First, I'd recommend that you backup any important personal data you may have on that drive, just to be on the safe side. After that I'd suggest that you download the HDD manufacturer's diagnostic tool and test the drive with it, to see if anything alarming pops-up. You could also try the HDD with a different computer to see if the same thing happens, because it might be caused by a faulty SATA cable or SATA port as well.
Also, download a RAM diagnostic tool to test the memory of the laptop, to see if it's working properly.
Hope that helps. Please let me know how everything goes.
Boogieman_WD