Computer not authorised to play song
I have recently purchased a couple of albums using iTunes on my iPhone. I have downloaded the albums in iTunes on my PC but some of the tracks won't play and a message tells me that the computer is not authorised. The tracks that won't play don't have me as the purchaser when I check the song / file info. The songs will also not sync onto an ipod. The albums play fine on my iPhone and streaming to my ipad through iTunes match.
Can anyone help?