Help please. I can't update anything from the music store onto my ipod.

I bought two songs this morning and couldn't update them onto my ipod. It said "Some of the songs in the itunes music library including the song..., were not copied to to the ipod because they cannot be played on this ipod." On the bottom of the screen it is telling me that it is a corrupt file, and to run the chksdk utility. I ran the utility and ti still didn't work. I updated the software on my ipod, and reloaded itunes onto my computer. I restored my ipod to factory settings, and then updated everything. Everything updated except those two songs. I bought another song to see if it was just a problem with those two individual songs, but the third song I bought today didn't work either. I don't know what to do.