Q: Music will not Authorize/Play

I have purchased several songs and albums from iTunes over the years, and have never had problems. All of a sudden a few random songs from different albums that I purchased will not play. I first saw this on my iPod Touch (it just wouldn't play, even if I hit the play button), and went on to my iTunes to find out why it wasn't playing. When I try to play it on iTunes, it says I need to authorize my computer to play it. I have authorized this computer many times, but every time I log in to authorize it, it says it is authorized and then when I go to play the song again, it asks me to authorize the computer again. I have tried this several times and it hasn't changed.

Help!