check the following to see if it helps:
http://docs.info.apple.com/article.html?artnum=61711
Thanks for the link, Jeff. Unfortunately, I've tried everything on the list up to the last option, Restore, and nothing has worked. So I went to restore my iPod, but then I realized I have a major problem: how can I restore my iPod if iTunes isn't recognizing it? It shows up in Windows Explorer, but when I pull up the iPod Updater software to restore, it inevitably tells me to plug in an iPod in order to update it, when my iPod is already plugged in.
I'd really appreciate any help anyone can offer me here. I'm really frustrated and I'd really like to fix this sometime in the next day or so because my iTunes is on my computer at school, I'm leaving for home for Thanksgiving break tomorrow afternoon, and I'd like to have all the new music I just bought on my iPod over break.
But once again, thanks to anyone who can give me any kind of advice!