Computer authorization

I purchase songs from the same computer and same account exclusively. There have been a couple of instances where I can not play the song on the computer I purchased it on. The computer is authorized, but when I try to play the song, it asks if I want to authorize the computer and even though it is authorized, I authorize it again, and I try to play the song, it asks if I want to authorize the computer again. I have purchased hundreds of song and only a few have done this. I can play them on my iphone or ipad, just not from the computer that I actually purchased them on. Any suggestions on how to fix this would be greatly appreciated.