Check for Updates
Any time you are having a problem with iTunes or your iPod, iPhone, or iPad, the first thing you should do is check for program or firmware updates. Apple regularly updates their software and you should make sure you have the latest updates, especially if something isn't working properly.
To update iTunes, just open iTunes and then go to Help in the top menu and choose 'Check for Updates'. Many computers are configured to automatically prompt you for iTunes and Quicktime updates even without running the software, so if your PC has been asking you to install those updates, you should do so.
To update your iPod Touch, iPhone, or iPad, open iTunes and then connect your device. Once connected, iTunes will periodically check for firmware updates, but you can manually check by clicking the 'Check for Updates' button on the main screen under the Devices section.
(Image credit: Screenshot taken from author's PC. Serial number digitally removed for security purposes)