Need help with my ipod touch please!?

So I got a 3rd generation Ipod touch for my birthday a few weeks ago and so far everything's been great. But today, I added a few songs and a movie to my Itunes library, and my ipod goes through the syncing process and everything, but at the end it says something like "This ipod couldn't be backed up because the backup is either corrupted or is the wrong type for this ipod. Delete the backup and try again." or something like that. At first I didn't think anything of this, but then I realized the new songs, and movie didn't sync. They show up in the itunes library, but they wont go onto my ipod touch. Any ideas on why? thanks. P.S. My ipod touch is NOT jailbroken.