https://www.techrepublic.com.com/5208-6230-0.html?forumID=101&threadID=263186&messageID=2495469
The hard drive may be failing.
If your laptop is somewhat ancient, perhaps the hard drive has had its life. You can download HD diagnostic software, burn it to a CD and boot your computer from the CD (if your laptop has a CD-ROM drive):
http://www.pcdocpro.com/z3/pcdocov.html?gclid=CNq5hJScn5MCFQ-7iQodsCf_zg
Others will probably post their favorite HD diagnostic utilities. I suspect most will do the job.
Before you order a replacement HD, consider the value of the laptop and whether you wish to install the HD yourself. Installation is actually a 10-minute do-it-yourself project, best attempted if your laptop is sacrificial.
I have found good deals on HDs at NewEgg.com:
http://www.newegg.com/Store/SubCategory.aspx?SubCategory=380&name=Laptop-Hard-Drives
There is a Western Digital 120GB 2.5" HD for $70 posted at NewEgg.com should you be interested.
Rick/Portland, OR