Hi there.
First thing you should do if you still can access the hard drive make a backup of your most important data on a different location (external drive, cloud, etc.).
Did you get any specific results from the second chkdsk test? Any errors, or everything was fine again? Also, you can run a diagnostic check with another program just to see if it will varify the results, or it will show something wrong with the device. Most of the HDD manufacturers have their own tool for such things, so you can check what your hard disk is, check in the official website of the manufacturer for a diagnostics program, and run a test with it. For instance, if it's WD you can download and use Data Lifeguard Diagnostics:
http://products.wdc.com/support/kb.ashx?id=PjaXDD
Let me know how it went.
My computer has been getting a HD Failure warning for a few weeks now. I ran chkdsk and the warning went away. I noticed that is was back the other day. i Re ran chkdsk again and it went away. Now it has reappeared. Any ideas?

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic