I would check out your hard drive's performance.
Acronis Drive Monitor will work and is free. I use this, it's really good. However, like all of these things, it's only as good as the signal route - IE, a bad cable may cause false positives etc so if you can also test the cable you will have the extra reassurance (and of course then the port on the motherboard! Although normally, the results are pretty accurate I just wanted to point out it could be something else.)
Acronis Drive Monitor: Estimate health percentage, and use Windows Event Log events (which may be related to risk of data loss). Can trigger automatic backup on S.M.A.R.T. alert when combined with Acronis backup software.
Wikipedia also gives you an overview of such S.M.A.R.T tools (too much to copy across).
One of the contributors to this site, Ramhound suggests SpinRite (from another post). Despite it saying XP at places, it should work for W8 fine.
The results of reports based on S.M.A.R.T data should be taken into context. Many of the problems HDDs have they are not even aware of. The best way to have a healthy drive is to run it through a program that will read each and every sector often. This allows the HDD to move data from bad sectors to good sectors and then mark any sectors it determines as bad as unusable. This is far more useful then say a defrag although it should be said, running a defrag, often does exactl this. One program I use for for all my HDDs is SpinRite. – Ramhound