Synchronizing iPod not working the way I expected

Factual Questions
1

This is a 20GB 3G iPod on Windows XP.

In the Music tab of my iPod settings, I have it set to synchronize two playlists. One is about 13 GB, and one is about 1GB. I also checked the “fill the rest of the iPod with music” box.

When I click the Sync button, I get an error/warning message that says that not all of the music I have selected will fit on the iPod, but that it’s going to put as much as it can. This is worrisome, since I only told it to put 14G on a 20G pod.

When it’s done synchronizing, I notice that

  1. It’s not full. There’s still a Gig or two of space left (even on the iTunes representation. I know that I won’t really have 20GB of music due to GB/GiB marketing, and formatting).
  2. There is music on there that isn’t in either of the playlists I told it to synchronize. It’s music that used to be on there, when I just let iTunes pick what to load.

I haven’t yet verified if everything I wanted on the iPod is on there, so it’s possible that everything worked fine and the only problem is that the error message about not fitting everything on shouldn’t have shown up. Or do I just misunderstand what iTunes thinks “synchronize” means? But, then, why is the iPod not full if the “Fill the rest of the iPod with music” button does what it claims t o do?

2

Have you tried reformatting the iPod? Right-click on it on the iTunes menu on the left.