Very, very, very rare defect
I had one of those iPods that randomly jumped from one song to another even while in the middle of a song. You might consider this skipping. I contacted Apple support and they told me it was a defect in the iPod somewhere. The people in Apple Support sent me a new one right away. We're talking a 3-day turnaround. They sent me an overnight printable shipping label. I shipped it and they shipped the replacement the next day! Awesome!
By the way, the same iPod that had the problem I described above was the 5th Generation video and it also had trouble loading the data into the memory card. Sometimes the HD woudn't spin up at all. There was a weird defect with the internal processing that would tell it when to spin up the HD to load data into the memory card.
In general, iPods do not exhibit this behavior. I have the very first iPod (5GB), the 3rd Generation iPod, the 4th Generation iPod (40GB) and now the 5th Generation iPod 60GB video. They are all awesome and work beautifully.
I just wanted to mention that defects can happen, but they are very rare... especially when it comes to Apple. And have no fear, their replacement policy and support is amazing.
Take Care,
Quark