if i aint mistaken , bad sectors can also be shown , because of corrupt data or fat . like the time i had first quater of my disk brand new 120gb showing up as bad sector . just took the manufactureres disk utilities and ran a couple of test and then bad sectors were gone and hdd is fine now .
i would suggest u take a backup of all ur data and then run the manufactureres utilies to test the hdd . usually there are two modes , one is non-destructive and other destructive . if u have too much info and cant backup , run the non-destructive tests and recovery of bad sectors , else after backing up run write zeros to drive .
most cases formatting disk again will improve its condition . plus physically remove the disk and clean it of dust , so as to reduce the temp of hdd too