Well, it just depends on a bad sector being marked during low level formatting. If it was OK at the time of the factory format, and then shipped as being good, it could have a bad sector that would show up in the same place every time if it went bad after. A low level format can fix that. Some drive vendors do let you get to the low level format...I believe that WD and Seagate did. Not sure if the utils are still available online. Anyway, I guess the safest thing to say at this point is "never mind". New drives have plenty of bad sectors that are skipped during a factory format. You never know that they are there...and usually never neet to.