Q: Some purchased songs not playing after moving to new computer

I migrated my music library to a new computer by moving the entire iTunes folder from the old computer to an external hard drive then to the new computer. When I synced my iPhone using the new computer, everything synced fine the first time except for an error saying three songs could not be converted properly. When I try to play the songs in iTunes, it tells me they are not authorized to play on the new computer then asks me to login to authorize (even though I already had logged in beforehand). Even after logging in again they won't play. The tracks won't play on the iPhone either.

The three tracks are part of a full album which I purchased via the music store on my iPhone. They synced to my old computer with no problem. They show up in my purchases section in iTunes. And the other 8 tracks from the same album work just fine. And I just double checked, and the tracks no longer play on the old machine either. The only weird thing was that when I synced it appeared as though iTunes downloaded the songs again even though they were already in the existing library. Any idea what's going on here and how to fix it?