hard drive pending sector count

Your Current Pending Sector Count (2163) is higher than the Reallocation Sector Count (252).
This means that failing sectors can no longer be replaced by the disk firmware.
The disk is failing - make sure you've backups, and get a replacement..

I'm new here, with no reputation, so I cannot affect the rating of answers above, but the green checked answer of Nov 13, 2009 at 8:42 is almost completely wrong! The first 2 sentences are completely wrong, comparing apples (raw count of 2163) to oranges (normalized score of 252). Reallocated_Sector_Ct is zero! That means not one sector has been remapped yet! And the Current_Pending_Sector count of 2163 sectors are questionable sectors, but not necessarily unusable sectors. They are not reclaimed or remapped until a write is made to the questionable sector, at which point the drive stops trying to preserve the contents of the sector and can thoroughly test its media, and decide whether to put it back online as good, or remap it, reallocating a spare sector into its LBA.

Sector data can be scrambled by power spikes, which cause them to fail their ECC info, and be marked as a Current_Pending_Sector. The next write will allow the drive to discover that the underlying media is fine, and reuse the sector, writing fresh data with fresh ECC info.

Please read the Wikipedia article on "S.M.A.R.T."

A Current_Pending_Sector count of 2163 is very worrying, and even more so is an Offline_Uncorrectable count of 19080. While not critical, a G-Sense_Error_Rate that is maxed out at 999999 is also somewhat alarming. That's a lot of physical jolts!