iTunes song won't download onto iPhone

I tried to download a song via iTunes on my iPhone 3G. Unfortunately the song won't download. When I go into the "Downloads" screen, the status says "Download error. Tap to retry." Tapping does nothing and I can't "swipe" to the right to try and delete the download. I have turned off the phone and restarted, downloaded other songs and podcasts, attempted to search for the same song and download it again all with no success. The song does not show up in my iPod as available to listen to. I wouldn't mind so much except that iTunes continuously prompts me to enter my password at seemingly random times throughout the day even when I am not in iTunes. Any suggestions?