AudiGuy said:
what does it mean wheb mactheripper detects a bad sector?
The big question is where? If it found a bad sector on the destination drive (your hard drive, presumably) then it is time to backup all of your data without delay.
Run Apple Hardware Test and/or TechTool and see if they corroborate any drive problems. If so, call AppleCare if it is still under warranty, otherwise start pricing out replacement hard drives.
If the bad sector is being reported is on the DVD then it;s probably a damaged disc, not much you can do.