And why could this (bad sectors) occur?

I'm not saying that this is your problem... but this kind of damage normally occurs when the read/write heads actually touch the disk platter. This can happen if the unit is jarred heavily while the heads are over the disk platter (normally they are parked away from the data area). But it would take a pretty good hit to do this -- these drives are rated at something like 150 G's impact resistance while operating, and 400 G's when turned off.

Listen carefully the next time you are synchronizing. If you hear a repetitive sound, like "CLICK click click (pause) CLICK click click...) that is a good indication that you have mechanical problems with your drive.

This is not the end of the world -- new drives are amazingly cheap, and thanks to Tony's FAQ are easy to install. The data (i.e., music) on the drive is what's valuable.

tanstaafl.