If your hard drive is still under warranty you should back-up all important data then return your hard drive for replacement from the original seller.
What they are: these are sectors or clusters--physical or logical locations--in the hard drive that are not accessible thus they cannot contain data. Many users report that sometimes logical bad sectors are "contagious"--meaning if you have them once, there is a tendency that they could propagate in the long run. Very often, a bad sector or cluster can cause the OS to fail during boot-up.
The causes of bad sector could be an overclocked PCI bus speeds, malware, extreme heat or moisture, jarred unit, old age (retired units which are refurbished and sold as used, or sometimes even as "new"), or general wear and tear. The most common cause would be extremes of heat or moisture or a mixture of both.
Sometimes bad sectors could be cured by low-formatting the drive using a DOS-level format disk from the HD manufacturer. Other format procedures--such as reformatting through Windows Explorer, however, only marks the sectors as bad, and thus you can't access them no longer.
You did not specify the size of your HD or the duration of its usage from installation, but you could attempt CHKDSK /r to recover data from the bad sector.